From rambiusparkisanius at gmail.com  Tue Dec  1 00:32:23 2020
From: rambiusparkisanius at gmail.com (Ivan "Rambius" Ivanov)
Date: Tue, 1 Dec 2020 00:32:23 -0500
Subject: Concatenating a Hash to a String
Message-ID: <CAE9rwzO-tNw2AYT9gZSd7jb0myXGX=7k3yn-Yb7_seOuMkMVHw@mail.gmail.com>

Hello,

I want to store the hashes of strings in a database and I have
problems generating the sql statements. I generate the hashes using
hashlib and then convert it to base64 and I put the base64
representation in the sql. Here is the code:

#!/usr/bin/env python3.8

import base64
import hashlib

def gen_sql(s):
  sha = hashlib.sha256()
  # need to encode s as binary, otherwise the next line throws
  # TypeError: Unicode-objects must be encoded before hashing
  sha.update(b"{s}")
  ehash = base64.b64encode(sha.digest())
  sql = "insert into HASHES value ('" + ehash + "')"

s = "test"
gen_sql(s)

This code throws

$ ./hashinstr.py
Traceback (most recent call last):
  File "./hashinstr.py", line 16, in <module>
    gen_sql(s)
  File "./hashinstr.py", line 13, in gen_sql
    sql = "insert into HASHES value ('" + ehash + "')"
TypeError: can only concatenate str (not "bytes") to str

Any help on how to concatenate ehash to the sql?

Regards
rambius

-- 
Tangra Mega Rock: http://www.radiotangra.com

From rosuav at gmail.com  Tue Dec  1 00:36:45 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 1 Dec 2020 16:36:45 +1100
Subject: Concatenating a Hash to a String
In-Reply-To: <CAE9rwzO-tNw2AYT9gZSd7jb0myXGX=7k3yn-Yb7_seOuMkMVHw@mail.gmail.com>
References: <CAE9rwzO-tNw2AYT9gZSd7jb0myXGX=7k3yn-Yb7_seOuMkMVHw@mail.gmail.com>
Message-ID: <CAPTjJmo=8NfS2Q5OyNo=30SV6y-OfYbSeEE9-td=PcYJjrf+zA@mail.gmail.com>

On Tue, Dec 1, 2020 at 4:34 PM Ivan "Rambius" Ivanov
<rambiusparkisanius at gmail.com> wrote:
>
> Hello,
>
> I want to store the hashes of strings in a database and I have
> problems generating the sql statements. I generate the hashes using
> hashlib and then convert it to base64 and I put the base64
> representation in the sql. Here is the code:
>
>   sql = "insert into HASHES value ('" + ehash + "')"
>

Don't do this! DO NOT do this! Even if it might happen to work with a
base 64 encoded value, this is a terrible terrible bug just waiting to
happen. Instead, use *parameterized queries* and keep your SQL safe.
Concatenating arbitrary data into an SQL statement is one of the top
ten most common and dangerous flaws in application code. Just don't do
it.

ChrisA

From rambiusparkisanius at gmail.com  Tue Dec  1 00:53:11 2020
From: rambiusparkisanius at gmail.com (Ivan "Rambius" Ivanov)
Date: Tue, 1 Dec 2020 00:53:11 -0500
Subject: Concatenating a Hash to a String
In-Reply-To: <CAPTjJmo=8NfS2Q5OyNo=30SV6y-OfYbSeEE9-td=PcYJjrf+zA@mail.gmail.com>
References: <CAE9rwzO-tNw2AYT9gZSd7jb0myXGX=7k3yn-Yb7_seOuMkMVHw@mail.gmail.com>
 <CAPTjJmo=8NfS2Q5OyNo=30SV6y-OfYbSeEE9-td=PcYJjrf+zA@mail.gmail.com>
Message-ID: <CAE9rwzNHhfovvhY5mmsiu+wN2KXn1dSGcL8LJ4kKFLSk8jOfLw@mail.gmail.com>

On Tue, Dec 1, 2020 at 12:39 AM Chris Angelico <rosuav at gmail.com> wrote:
> Don't do this! DO NOT do this! Even if it might happen to work with a
> base 64 encoded value, this is a terrible terrible bug just waiting to
> happen. Instead, use *parameterized queries* and keep your SQL safe.

OK. What are parameterized queries? Can you give an example?

-- 
Tangra Mega Rock: http://www.radiotangra.com

From rosuav at gmail.com  Tue Dec  1 01:00:07 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 1 Dec 2020 17:00:07 +1100
Subject: Concatenating a Hash to a String
In-Reply-To: <CAE9rwzNHhfovvhY5mmsiu+wN2KXn1dSGcL8LJ4kKFLSk8jOfLw@mail.gmail.com>
References: <CAE9rwzO-tNw2AYT9gZSd7jb0myXGX=7k3yn-Yb7_seOuMkMVHw@mail.gmail.com>
 <CAPTjJmo=8NfS2Q5OyNo=30SV6y-OfYbSeEE9-td=PcYJjrf+zA@mail.gmail.com>
 <CAE9rwzNHhfovvhY5mmsiu+wN2KXn1dSGcL8LJ4kKFLSk8jOfLw@mail.gmail.com>
Message-ID: <CAPTjJmpPuLM0evZmuJF+Gcyvs3EoEE108UL0QSMEoGhV-sLaUQ@mail.gmail.com>

On Tue, Dec 1, 2020 at 4:53 PM Ivan "Rambius" Ivanov
<rambiusparkisanius at gmail.com> wrote:
>
> On Tue, Dec 1, 2020 at 12:39 AM Chris Angelico <rosuav at gmail.com> wrote:
> > Don't do this! DO NOT do this! Even if it might happen to work with a
> > base 64 encoded value, this is a terrible terrible bug just waiting to
> > happen. Instead, use *parameterized queries* and keep your SQL safe.
>
> OK. What are parameterized queries? Can you give an example?
>

I've no idea what database you're connecting to, what library you're
using, or anything, but it would look something like this:

conn.execute("insert into hashes values (?)", [hash])

Look up the documentation for what you're working with. It will have a
way to do this.

ChrisA

From doctor at doctor.nl2k.ab.ca  Tue Dec  1 10:02:19 2020
From: doctor at doctor.nl2k.ab.ca (The Doctor)
Date: Tue, 1 Dec 2020 15:02:19 -0000 (UTC)
Subject: XanaNews Statistic for comp.lang.python.  12/1/2020 8:02:16 AM
Message-ID: <rq5ltr$kpc$36@gallifrey.nk.ca>

XanaNews Statistic for comp.lang.python.  12/1/2020 8:02:16 AM

>From article 584939 (11/1/2020 3:10:51 AM) to article 585435
(11/30/2020 11:00:07 PM)

Number of threads  ................... 200
Number of articles  .................. 538
Average articles per thread  ......... 2.69
Number of unanswered posts  .......... 137
Number of posts from XanaNews users .. 0


Top Threads

Ranking  Articles  Subject
-------  --------  ----------------------------------
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      6        13  Python Error
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      8        10  Class Definitions
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     14         7  A problem with opening a file
     15         7  numpy problem (follow up)
     16         7  constant folding - why not more
     17         7  Getting rid of virtual environments with a better
dependency system
     18         7  Any better way for this removal?
     19         7  How can I make this more complex?
     20         7  A problem with opening a file -- again
     21         7  Re: Best way to determine user's screensize?
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     23         6  Reading binary data with the CSV module
     24         5  try/except in loop
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     27         5  Please help test astral char display in tkinter Text
(especially *nix)
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     29         5  answer not correct
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names must be tokens
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     33         5  Any experience with Python for GraalVM ?
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application
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     37         4  Re: ? DA ARRESTARE L'AVVOCATO ASSASSINO DANIELE
MINOTTI
     38         4  How to run Jupyter notebook in command line and get
full error message?
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     40         4  Problem with rearanging list with paired letters
next to each others
     41         4  Error issue - Kindly resolve
     42         4  EuroPython "Ask me Anything" - Nov Edition
     43         4  Help
     44         4  Need help in installing numpy
     45         4  IDEL from Windows It does not work
     46         4  Python 3
     47         4  series.py, cannot import series from pandas
     48         4  EuroPython videos all on archive.org
     49         4  ssl connection has been closed unexpectedly
     50         3  Best-practice for formatted string literals and
localization?
     51         3  Getting rid of virtual environments with a better
dependency system
     52         3  Re: GUI: I am also looking for a nudge into the best
(GUI) direction.
     53         3  io.TextIOWrapper.readlines
     54         3  I have no clue figuring out how to check dates in
workholidays
     55         3  Tkinter List of Canvases
     56         3  asyncio question
     57         3  Automatically advancing a bi-directional generator
to the point of accepting a non-None value?
     58         3  Converting images to PDF. Final file has blank pages
before and after.
     59         3  filtering out warnings
     60         3  unable to use numpy
     61         2  Re: songbird's ngfp
     62         2  Seeking guidance to start a career in python
programming
     63         2  Extending the Python terminology


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      5        15  Bischoop                    slrn                     
      6        14  MRAB                        Mozilla                  
      7        14  Stefan Ram                                           
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     20         6  Jason Friedman                                       
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From dieter at handshake.de  Tue Dec  1 13:32:00 2020
From: dieter at handshake.de (Dieter Maurer)
Date: Tue, 1 Dec 2020 19:32:00 +0100
Subject: Concatenating a Hash to a String
In-Reply-To: <CAE9rwzO-tNw2AYT9gZSd7jb0myXGX=7k3yn-Yb7_seOuMkMVHw@mail.gmail.com>
References: <CAE9rwzO-tNw2AYT9gZSd7jb0myXGX=7k3yn-Yb7_seOuMkMVHw@mail.gmail.com>
Message-ID: <24518.35872.22642.795263@ixdm.fritz.box>

"Ivan \"Rambius\" Ivanov" wrote at 2020-12-1 00:32 -0500:
> ...
>This code throws
>
>$ ./hashinstr.py
>Traceback (most recent call last):
>  File "./hashinstr.py", line 16, in <module>
>    gen_sql(s)
>  File "./hashinstr.py", line 13, in gen_sql
>    sql = "insert into HASHES value ('" + ehash + "')"
>TypeError: can only concatenate str (not "bytes") to str

With Python 3, you must carefully distinquish `bytes` (a
sequence of numbers between 0 and 255) and `str` (a sequence of
(unicode) characters).
`base64` operates on `bytes`; `"..."` constructs an `str`;
Python 3 has made `bytes` and `str` (mostly) incompatible.

You can use `.decode([charset, error])` to convert `bytes` to `str`
and `.encode([charset, error])` to convert `str` to `bytes`.

Because `base64.encode` gives you a sequence of values between 0 and 127,
you can omit the optional parameters for `.decode`.

From python at mrabarnett.plus.com  Tue Dec  1 13:30:21 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 1 Dec 2020 18:30:21 +0000
Subject: Concatenating a Hash to a String
In-Reply-To: <CAE9rwzO-tNw2AYT9gZSd7jb0myXGX=7k3yn-Yb7_seOuMkMVHw@mail.gmail.com>
References: <CAE9rwzO-tNw2AYT9gZSd7jb0myXGX=7k3yn-Yb7_seOuMkMVHw@mail.gmail.com>
Message-ID: <28356456-6624-dec3-8415-ed9a224f2676@mrabarnett.plus.com>

On 2020-12-01 05:32, Ivan "Rambius" Ivanov wrote:
> Hello,
> 
> I want to store the hashes of strings in a database and I have
> problems generating the sql statements. I generate the hashes using
> hashlib and then convert it to base64 and I put the base64
> representation in the sql. Here is the code:
> 
> #!/usr/bin/env python3.8
> 
> import base64
> import hashlib
> 
> def gen_sql(s):
>    sha = hashlib.sha256()
>    # need to encode s as binary, otherwise the next line throws
>    # TypeError: Unicode-objects must be encoded before hashing
>    sha.update(b"{s}")
>    ehash = base64.b64encode(sha.digest())
>    sql = "insert into HASHES value ('" + ehash + "')"
> 
> s = "test"
> gen_sql(s)
> 
> This code throws
> 
> $ ./hashinstr.py
> Traceback (most recent call last):
>    File "./hashinstr.py", line 16, in <module>
>      gen_sql(s)
>    File "./hashinstr.py", line 13, in gen_sql
>      sql = "insert into HASHES value ('" + ehash + "')"
> TypeError: can only concatenate str (not "bytes") to str
> 
> Any help on how to concatenate ehash to the sql?
> 
The bytes are all in the ASCII range, so you can convert it into a 
string using .decode('ascii').

And, of course, use parametrised queries, as ChrisA said.

From dieter at handshake.de  Tue Dec  1 13:40:29 2020
From: dieter at handshake.de (Dieter Maurer)
Date: Tue, 1 Dec 2020 19:40:29 +0100
Subject: Best-practice for formatted string literals and localization?
In-Reply-To: <677f5213-9d52-0289-4152-b2a9190f7fe1@crazy-compilers.com>
References: <677f5213-9d52-0289-4152-b2a9190f7fe1@crazy-compilers.com>
Message-ID: <24518.36381.933046.754777@ixdm.fritz.box>

Hartmut Goebel wrote at 2020-11-30 19:30 +0100:
>formatted string literals are great, but can't be used together with
>localization:
>
>    _(f"These are {count} stones")
>
>will crash babel ("NameError: name 'count' is not defined".

Translations are kept in external files (without any runtime
association).
As a consequence, they cannot contain runtime entities;
and therefore, you should not use f-strings for internationalizations.

Usually, the translation machinery has special ways to
provide parameters for translations.
For example with `zope.i18nmessageid`, you can use
`_(msg, mapping=<parameter_dict>)` to provide parameters
to the translations -- as in your case `count`).
Check, what parameter support your translation machinery support.

From alvarodorsnestares at gmail.com  Tue Dec  1 03:53:46 2020
From: alvarodorsnestares at gmail.com (=?UTF-8?Q?=C3=81lvaro_d=27Ors?=)
Date: Tue, 1 Dec 2020 09:53:46 +0100
Subject: Bot
Message-ID: <CAFnUUM=r0xYjoKgBFK8WoSzufGo05b_F5mBduyu=T7oes-oytQ@mail.gmail.com>

Hi guys, I'm new here, can anyone help me built a bot than can input data
in a website?
This is not for spam purposes, I just need to reserve a place in the
library at the university but they are completed in a matter of minutes and
I can't waste time "camping" the website. Thank you

Nestares D. ?lvaro

From ikorot01 at gmail.com  Tue Dec  1 22:15:52 2020
From: ikorot01 at gmail.com (Igor Korot)
Date: Tue, 1 Dec 2020 21:15:52 -0600
Subject: IDLE error
In-Reply-To: <CAFnUUMnjjO4O0pZWyTW2LOFYJt4RwYOca34pZMo_RKtag6DcuQ@mail.gmail.com>
References: <CAFnUUMnjjO4O0pZWyTW2LOFYJt4RwYOca34pZMo_RKtag6DcuQ@mail.gmail.com>
Message-ID: <CA+FnnTx6N-xXfWc6Hr0tvppLQzjjwyMR1zpsXYD28_42NFi7Pw@mail.gmail.com>

Hi, Alvaro,

On Tue, Dec 1, 2020 at 9:11 PM ?lvaro d'Ors
<alvarodorsnestares at gmail.com> wrote:
>
> The IDLE seems to be malfunctioning, I just re-installed Python and used
> the reapir function but I can?t open the IDLE, please help.

What OS do you use?
Are you trying to run it by double-clicking on the icon?
What happens? Does it give you any error?

Thank you.

>
>
>
> --
> Nestares D. ?lvaro
> --
> https://mail.python.org/mailman/listinfo/python-list

From PythonList at DancesWithMice.info  Wed Dec  2 00:02:44 2020
From: PythonList at DancesWithMice.info (dn)
Date: Wed, 2 Dec 2020 18:02:44 +1300
Subject: Bot
In-Reply-To: <CAFnUUM=r0xYjoKgBFK8WoSzufGo05b_F5mBduyu=T7oes-oytQ@mail.gmail.com>
References: <CAFnUUM=r0xYjoKgBFK8WoSzufGo05b_F5mBduyu=T7oes-oytQ@mail.gmail.com>
Message-ID: <b930d57a-5d02-4304-d873-5df391e15286@DancesWithMice.info>

On 01/12/2020 21:53, ?lvaro d'Ors wrote:
> Hi guys, I'm new here, can anyone help me built a bot than can input data
> in a website?
> This is not for spam purposes, I just need to reserve a place in the
> library at the university but they are completed in a matter of minutes and
> I can't waste time "camping" the website. Thank you


https://duckduckgo.com/?q=python+web+form+fill
- the third or fourth response seemed to handle a log-on screen.

Although if you're prepared to pay for their time, others may be able to 
save your time...
-- 
Regards =dn

From rambiusparkisanius at gmail.com  Wed Dec  2 01:24:40 2020
From: rambiusparkisanius at gmail.com (Ivan "Rambius" Ivanov)
Date: Wed, 2 Dec 2020 01:24:40 -0500
Subject: Concatenating a Hash to a String
In-Reply-To: <28356456-6624-dec3-8415-ed9a224f2676@mrabarnett.plus.com>
References: <CAE9rwzO-tNw2AYT9gZSd7jb0myXGX=7k3yn-Yb7_seOuMkMVHw@mail.gmail.com>
 <28356456-6624-dec3-8415-ed9a224f2676@mrabarnett.plus.com>
Message-ID: <CAE9rwzMfWQ_3m=H=R2XRyDTomoJtyUN6SU8cYW9aDDoebXCZCw@mail.gmail.com>

Hello,

Thank you all for your help.

On Tue, Dec 1, 2020 at 1:38 PM MRAB <python at mrabarnett.plus.com> wrote:
> The bytes are all in the ASCII range, so you can convert it into a
> string using .decode('ascii').
I utilized encode and decode string methods to convert from bytes to strings

> And, of course, use parametrised queries, as ChrisA said.
I am using sqlite3 and it supports parameterized queries. Overall they
are better than constructing the sql statements manually.

Regards and thanks
rambius


-- 
Tangra Mega Rock: http://www.radiotangra.com

From Marco.Sulla.Python at gmail.com  Wed Dec  2 06:33:45 2020
From: Marco.Sulla.Python at gmail.com (Marco Sulla)
Date: Wed, 2 Dec 2020 12:33:45 +0100
Subject: Bot
In-Reply-To: <CAFnUUM=r0xYjoKgBFK8WoSzufGo05b_F5mBduyu=T7oes-oytQ@mail.gmail.com>
References: <CAFnUUM=r0xYjoKgBFK8WoSzufGo05b_F5mBduyu=T7oes-oytQ@mail.gmail.com>
Message-ID: <CABbU2U99Axztb8uBtUS73gGFDUQxxGZwNSYf4VWU3ijr8Lx2FQ@mail.gmail.com>

On Wed, 2 Dec 2020 at 04:13, ?lvaro d'Ors <alvarodorsnestares at gmail.com> wrote:
>
> Hi guys, I'm new here, can anyone help me built a bot than can input data
> in a website?

I never used it, but you can try Chatterbot:
https://chatterbot.readthedocs.io/en/stable/

From priyankgasree10 at gmail.com  Wed Dec  2 12:57:39 2020
From: priyankgasree10 at gmail.com (Priyankgasree K)
Date: Wed, 2 Dec 2020 12:57:39 -0500
Subject: problem in installation of python 3.9.0
Message-ID: <CAKC1Y=6JRL+-mwQAYwSQpo_Tmk8z2bGLUih6y5EAp=3r_suZOw@mail.gmail.com>

Hello,
        I am Priyankgasree, i am facing problem in installing python3.9.0.
after i finish download it always says you have to repair or uninstall. I
have repaired and uninstalled and reinstalled several times but i can't do
anything . And also I cant able to download other versions of python. So
tell me what`s the problem and the solution

From mats at wichmann.us  Wed Dec  2 12:44:31 2020
From: mats at wichmann.us (Mats Wichmann)
Date: Wed, 2 Dec 2020 10:44:31 -0700
Subject: problem in installation of python 3.9.0
In-Reply-To: <CAKC1Y=6JRL+-mwQAYwSQpo_Tmk8z2bGLUih6y5EAp=3r_suZOw@mail.gmail.com>
References: <CAKC1Y=6JRL+-mwQAYwSQpo_Tmk8z2bGLUih6y5EAp=3r_suZOw@mail.gmail.com>
Message-ID: <72326096-f72d-6881-9d34-f3675152148c@wichmann.us>

On 12/2/20 10:57 AM, Priyankgasree K wrote:
> Hello,
>          I am Priyankgasree, i am facing problem in installing python3.9.0.
> after i finish download it always says you have to repair or uninstall. I
> have repaired and uninstalled and reinstalled several times but i can't do
> anything . And also I cant able to download other versions of python. So
> tell me what`s the problem and the solution

Don't rerun the installer.  That's its purpose: to let you install, or 
modify the existing installation.  You can remove the downloaded 
installer after you're done with it.

Instead, either run Python from a shell - use the command name py if you 
installed the Python launcher.  Or use the Windows search box to look 
for the command named python, the match you want should looke something 
like "Python 3.9 (64-bit)  App"


From drsalists at gmail.com  Wed Dec  2 12:58:38 2020
From: drsalists at gmail.com (Dan Stromberg)
Date: Wed, 2 Dec 2020 09:58:38 -0800
Subject: problem in installation of python 3.9.0
In-Reply-To: <72326096-f72d-6881-9d34-f3675152148c@wichmann.us>
References: <CAKC1Y=6JRL+-mwQAYwSQpo_Tmk8z2bGLUih6y5EAp=3r_suZOw@mail.gmail.com>
 <72326096-f72d-6881-9d34-f3675152148c@wichmann.us>
Message-ID: <CAGGBd_ry2V=02bmwqedAO8a4MZevhyXJajDxjKiHvOVr5Y1veA@mail.gmail.com>

On Wed, Dec 2, 2020 at 9:45 AM Mats Wichmann <mats at wichmann.us> wrote:

> On 12/2/20 10:57 AM, Priyankgasree K wrote:
> > Hello,
> >          I am Priyankgasree, i am facing problem in installing
> python3.9.0.
> > after i finish download it always says you have to repair or uninstall. I
> > have repaired and uninstalled and reinstalled several times but i can't
> do
> > anything . And also I cant able to download other versions of python. So
> > tell me what`s the problem and the solution
>
> Don't rerun the installer.  That's its purpose: to let you install, or
> modify the existing installation.  You can remove the downloaded
> installer after you're done with it.
>
> Instead, either run Python from a shell - use the command name py if you
> installed the Python launcher.  Or use the Windows search box to look
> for the command named python, the match you want should looke something
> like "Python 3.9 (64-bit)  App"
>
This seems to be a common question and answer.

Perhaps the installer could be named better, or Python could provide a
shortcut for itself?

From mats at wichmann.us  Wed Dec  2 13:02:26 2020
From: mats at wichmann.us (Mats Wichmann)
Date: Wed, 2 Dec 2020 11:02:26 -0700
Subject: problem in installation of python 3.9.0
In-Reply-To: <CAGGBd_ry2V=02bmwqedAO8a4MZevhyXJajDxjKiHvOVr5Y1veA@mail.gmail.com>
References: <CAKC1Y=6JRL+-mwQAYwSQpo_Tmk8z2bGLUih6y5EAp=3r_suZOw@mail.gmail.com>
 <72326096-f72d-6881-9d34-f3675152148c@wichmann.us>
 <CAGGBd_ry2V=02bmwqedAO8a4MZevhyXJajDxjKiHvOVr5Y1veA@mail.gmail.com>
Message-ID: <850454cb-733a-ea3b-4124-985b24cb2ffd@wichmann.us>


On 12/2/20 10:58 AM, Dan Stromberg wrote:

>     Don't rerun the installer.  


> This seems to be a common question and answer.


It certainly does...

> Perhaps the installer could be named better, or Python could provide a 
> shortcut for itself?
> 


I know it makes proper start menu entries for itself, but I guess people 
don't much look at those any longer? (dunno, I'm not primarily a Windows 
user).

From barry at barrys-emacs.org  Wed Dec  2 13:14:25 2020
From: barry at barrys-emacs.org (Barry)
Date: Wed, 2 Dec 2020 18:14:25 +0000
Subject: problem in installation of python 3.9.0
In-Reply-To: <CAGGBd_ry2V=02bmwqedAO8a4MZevhyXJajDxjKiHvOVr5Y1veA@mail.gmail.com>
References: <CAGGBd_ry2V=02bmwqedAO8a4MZevhyXJajDxjKiHvOVr5Y1veA@mail.gmail.com>
Message-ID: <33388FC6-30C2-48E0-85CA-30700C6124E8@barrys-emacs.org>



> On 2 Dec 2020, at 18:01, Dan Stromberg <drsalists at gmail.com> wrote:
> 
> ?On Wed, Dec 2, 2020 at 9:45 AM Mats Wichmann <mats at wichmann.us> wrote:
> 
>>> On 12/2/20 10:57 AM, Priyankgasree K wrote:
>>> Hello,
>>>         I am Priyankgasree, i am facing problem in installing
>> python3.9.0.
>>> after i finish download it always says you have to repair or uninstall. I
>>> have repaired and uninstalled and reinstalled several times but i can't
>> do
>>> anything . And also I cant able to download other versions of python. So
>>> tell me what`s the problem and the solution
>> 
>> Don't rerun the installer.  That's its purpose: to let you install, or
>> modify the existing installation.  You can remove the downloaded
>> installer after you're done with it.
>> 
>> Instead, either run Python from a shell - use the command name py if you
>> installed the Python launcher.  Or use the Windows search box to look
>> for the command named python, the match you want should looke something
>> like "Python 3.9 (64-bit)  App"
>> 
> This seems to be a common question and answer.
> 
> Perhaps the installer could be named better, or Python could provide a
> shortcut for itself?

You mean like including the word setup or installer in the file name?
That?s what everybody else does isn?t it?

Barry

> -- 
> https://mail.python.org/mailman/listinfo/python-list
> 


From shariesk at sundaelectronics.com  Wed Dec  2 18:36:40 2020
From: shariesk at sundaelectronics.com (Shari Eskenas)
Date: Wed, 2 Dec 2020 15:36:40 -0800 (PST)
Subject: A picture book written with Python programs
Message-ID: <e48c3747-eec2-4a7a-82b8-873aba4ffdc1n@googlegroups.com>

A Day in Code: Python is an educational book that tells a story through Python programs that represent real-life situations. Each program introduces a new Python programming concept.  It is currently a Kickstarter project: https://www.kickstarter.com/projects/914595512/a-day-in-code-python

From jesterdev at gmail.com  Wed Dec  2 22:32:21 2020
From: jesterdev at gmail.com (Michael Baca)
Date: Wed, 2 Dec 2020 19:32:21 -0800 (PST)
Subject: Converting images to PDF. Final file has blank pages before and
 after.
In-Reply-To: <mailman.262.1606788905.7193.python-list@python.org>
References: <68ed4193-21df-f5c9-f23e-93315ff92574@mrabarnett.plus.com>
 <8a0c04c4-3704-4c0d-8888-91df28f8e11dn@googlegroups.com>
 <mailman.262.1606788905.7193.python-list@python.org>
Message-ID: <f08b304d-7dd2-4b50-8bf8-727e4797e1e5n@googlegroups.com>

On Monday, November 30, 2020 at 7:15:37 PM UTC-7, MRAB wrote:
> On 2020-12-01 01:20, Michael Baca wrote: 
> > Hello, new to the group, rather new to programming. 
> > 
> > I'm writing a program that takes images and converts them into PDF's. It works after quite a few days of trying, however the final file has a blank page inserted before and after each page containing the images. 
> > 
> > This uses FPDF to do the conversion. I've been up and down trying to figure out where I'm adding an extra page, so it might be an FPDF issue. 
> > 
> > def multi_convert(pdf_Filename, file_path): 
> > if (dir): 
> > file_list = [] 
> > print(""), print("") 
> > print("Converting... This may take awhile depending on the number of images.") 
> > 
> > for entry in os.scandir(file_path): 
> > if (entry.path.endswith(".jpg") or entry.path.endswith(".png")) and entry.is_file(): 
> > file_list.append(entry.path) 
> > else: 
> > print("Error: ") 
> > print("Invalid Directory - {}", dir) 
> > cover = Image.open(str(file_list[0])) 
> > width, height = cover.size 
> > 
> > pdf = FPDF(unit="pt", format=[width, height]) 
> > 
> > for page in file_list: 
> > pdf.add_page() 
> > pdf.image(str(page)) 
> > 
> > pdf.output(file_path + pdf_Filename + ".pdf", "F") 
> > exit() 
> >
> It says in the documentation for the .image method: 
> 
> """ 
> x: 
> 
> Abscissa of the upper-left corner. If not specified or equal to None, 
> the current abscissa is used (version 1.7.1 and up). 
> 
> y: 
> 
> Ordinate of the upper-left corner. If not specified or equal to None, 
> the current ordinate is used; moreover, a page break is triggered first 
> if necessary (in case automatic page breaking is enabled) and, after the 
> call, the current ordinate is moved to the bottom of the image (version 
> 1.7.1 and up). 
> """ 
> 
> In other words, you're not specifying where the top-left corner of the 
> image should go, so it's putting it at the current position, wherever 
> that is, and it's responding to the positioning by inserting additional 
> pages. 
> 
> The solution is to specify the images' positions, and, perhaps, also 
> their sizes, if necessary. 
> 
> By the way, why doesn't the function end with "exit()"? That'll make it 
> exit the Python completely; rarely a good idea.

Thank you very much for the help. That makes sense, as I remember reading about the image placement, but I didn't think it mattered. My use is very simple, I occasionally need to covert images into to PDF's and this makes it easier than going online. So I figured it was okay to leave that out. I need to go back and read the  manual some more. 

It's a CLI program, it takes a few different arguments and when it's done it just returns to the shell. That's why I have the exit() where I do. Is there a better/safer way to exit the program?

From python at mrabarnett.plus.com  Thu Dec  3 06:55:13 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Thu, 3 Dec 2020 11:55:13 +0000
Subject: Converting images to PDF. Final file has blank pages before and
 after.
In-Reply-To: <f08b304d-7dd2-4b50-8bf8-727e4797e1e5n@googlegroups.com>
References: <68ed4193-21df-f5c9-f23e-93315ff92574@mrabarnett.plus.com>
 <8a0c04c4-3704-4c0d-8888-91df28f8e11dn@googlegroups.com>
 <mailman.262.1606788905.7193.python-list@python.org>
 <f08b304d-7dd2-4b50-8bf8-727e4797e1e5n@googlegroups.com>
Message-ID: <e542da2f-ec06-f866-fc56-5d902f308898@mrabarnett.plus.com>

On 2020-12-03 03:32, Michael Baca wrote:
> On Monday, November 30, 2020 at 7:15:37 PM UTC-7, MRAB wrote:
>> On 2020-12-01 01:20, Michael Baca wrote: 
>> > Hello, new to the group, rather new to programming. 
>> > 
>> > I'm writing a program that takes images and converts them into PDF's. It works after quite a few days of trying, however the final file has a blank page inserted before and after each page containing the images. 
>> > 
>> > This uses FPDF to do the conversion. I've been up and down trying to figure out where I'm adding an extra page, so it might be an FPDF issue. 
>> > 
>> > def multi_convert(pdf_Filename, file_path): 
>> > if (dir): 
>> > file_list = [] 
>> > print(""), print("") 
>> > print("Converting... This may take awhile depending on the number of images.") 
>> > 
>> > for entry in os.scandir(file_path): 
>> > if (entry.path.endswith(".jpg") or entry.path.endswith(".png")) and entry.is_file(): 
>> > file_list.append(entry.path) 
>> > else: 
>> > print("Error: ") 
>> > print("Invalid Directory - {}", dir) 
>> > cover = Image.open(str(file_list[0])) 
>> > width, height = cover.size 
>> > 
>> > pdf = FPDF(unit="pt", format=[width, height]) 
>> > 
>> > for page in file_list: 
>> > pdf.add_page() 
>> > pdf.image(str(page)) 
>> > 
>> > pdf.output(file_path + pdf_Filename + ".pdf", "F") 
>> > exit() 
>> >
>> It says in the documentation for the .image method: 
>> 
>> """ 
>> x: 
>> 
>> Abscissa of the upper-left corner. If not specified or equal to None, 
>> the current abscissa is used (version 1.7.1 and up). 
>> 
>> y: 
>> 
>> Ordinate of the upper-left corner. If not specified or equal to None, 
>> the current ordinate is used; moreover, a page break is triggered first 
>> if necessary (in case automatic page breaking is enabled) and, after the 
>> call, the current ordinate is moved to the bottom of the image (version 
>> 1.7.1 and up). 
>> """ 
>> 
>> In other words, you're not specifying where the top-left corner of the 
>> image should go, so it's putting it at the current position, wherever 
>> that is, and it's responding to the positioning by inserting additional 
>> pages. 
>> 
>> The solution is to specify the images' positions, and, perhaps, also 
>> their sizes, if necessary. 
>> 
>> By the way, why doesn't the function end with "exit()"? That'll make it 
>> exit the Python completely; rarely a good idea.
> 
> Thank you very much for the help. That makes sense, as I remember reading about the image placement, but I didn't think it mattered. My use is very simple, I occasionally need to covert images into to PDF's and this makes it easier than going online. So I figured it was okay to leave that out. I need to go back and read the  manual some more.
> 
> It's a CLI program, it takes a few different arguments and when it's done it just returns to the shell. That's why I have the exit() where I do. Is there a better/safer way to exit the program?
> 
It's best if a function just returns to its caller. That's what you'd 
expect a function to do, and it's a good practice to follow because it 
reduces the number of unexpected "surprises" in the long term or if you 
come back to the code much later.

From thomasomea at gmail.com  Thu Dec  3 07:13:59 2020
From: thomasomea at gmail.com (A. M. Thomas [PETech MIET MBA])
Date: Thu, 3 Dec 2020 15:13:59 +0300
Subject: Unable to read .xlsx file using pandas
Message-ID: <CAGey3pC96E+AvE_96+xr6kGTgpyFeJvPU=UwV+b+OrnmvQBT3Q@mail.gmail.com>

Kindly help manage read .xlsx files using pandas, thank you

import numpy as np
import pandas as pd
from pandas import Series, DataFrame

excelfile = pd.ExcelFile('C:\Users\THOMAS\Documents/Hash Analytics
Internship - DemoS2.xlsx')
dframe = excelfile.parse('Sheet10')
print (dframe)


C:\Users\THOMAS\AppData\Local\Programs\Python\Python39\python.exe
"C:/Users/THOMAS/PycharmProjects/Assignment#2/code File.py"
  File "C:\Users\THOMAS\PycharmProjects\Assignment#2\code File.py", line 5
    excelfile = pd.ExcelFile('C:\Users\THOMAS\Documents/Hash Analytics
Internship - DemoS2.xlsx')

                    ^
SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes in
position 2-3: truncated \UXXXXXXXX escape

Process finished with exit code 1
-- 
Best Regards,

*A. M. Thomas*
Electrical & Solar Systems Expert
*THE GUY BEHIND THE SCENE*
Cell: +254 723 309 157 / +254 731 406 125
Email: thomasomea at gmail.com / thomaso.engineer at gmail.com

"Alternative energy for real and sustainable development that we need"

From python at mrabarnett.plus.com  Thu Dec  3 07:54:54 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Thu, 3 Dec 2020 12:54:54 +0000
Subject: Unable to read .xlsx file using pandas
In-Reply-To: <CAGey3pC96E+AvE_96+xr6kGTgpyFeJvPU=UwV+b+OrnmvQBT3Q@mail.gmail.com>
References: <CAGey3pC96E+AvE_96+xr6kGTgpyFeJvPU=UwV+b+OrnmvQBT3Q@mail.gmail.com>
Message-ID: <68d2e1a5-d255-2d5c-6f41-9fe5f21ec677@mrabarnett.plus.com>

On 2020-12-03 12:13, A. M. Thomas [PETech MIET MBA] wrote:
> Kindly help manage read .xlsx files using pandas, thank you
> 
> import numpy as np
> import pandas as pd
> from pandas import Series, DataFrame
> 
> excelfile = pd.ExcelFile('C:\Users\THOMAS\Documents/Hash Analytics
> Internship - DemoS2.xlsx')
> dframe = excelfile.parse('Sheet10')
> print (dframe)
> 
> 
> C:\Users\THOMAS\AppData\Local\Programs\Python\Python39\python.exe
> "C:/Users/THOMAS/PycharmProjects/Assignment#2/code File.py"
>    File "C:\Users\THOMAS\PycharmProjects\Assignment#2\code File.py", line 5
>      excelfile = pd.ExcelFile('C:\Users\THOMAS\Documents/Hash Analytics
> Internship - DemoS2.xlsx')
> 
>                      ^
> SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes in
> position 2-3: truncated \UXXXXXXXX escape
> 
> Process finished with exit code 1
> 
You're giving the path as a plain string that contains \U, which is the 
start of an escape sequence, but it's not a valid escape sequence, hence 
the error.

You could use a raw string:

     r'C:\Users\THOMAS\Documents/Hash Analytics Internship - DemoS2.xlsx'

or escape the backslashes:

     'C:\\Users\\THOMAS\\Documents/Hash Analytics Internship - DemoS2.xlsx'

or use slashes instead of backslashes:

     'C:/Users/THOMAS/Documents/Hash Analytics Internship - DemoS2.xlsx'

From shishaozhong at gmail.com  Thu Dec  3 08:10:00 2020
From: shishaozhong at gmail.com (Shaozhong SHI)
Date: Thu, 3 Dec 2020 13:10:00 +0000
Subject: Observing long running processes of Jupyter Notebook
Message-ID: <CA+i5JwbL64rF41HX-L1Ji7mVJU=f2yTaJf1TNFB1BUb=h_t4-Q@mail.gmail.com>

We have been running Jupyter Notebook processes, which take long time to
run.

We use nbconvert to run these in commandline.  Nbconvert only writes output
into a file at the end.

We just wonder whether there is a way to observe the progress and printing
messages when nbconvert is running.

Regards,

David

From Marco.Sulla.Python at gmail.com  Thu Dec  3 11:41:57 2020
From: Marco.Sulla.Python at gmail.com (Marco Sulla)
Date: Thu, 3 Dec 2020 17:41:57 +0100
Subject: Observing long running processes of Jupyter Notebook
In-Reply-To: <CA+i5JwbL64rF41HX-L1Ji7mVJU=f2yTaJf1TNFB1BUb=h_t4-Q@mail.gmail.com>
References: <CA+i5JwbL64rF41HX-L1Ji7mVJU=f2yTaJf1TNFB1BUb=h_t4-Q@mail.gmail.com>
Message-ID: <CABbU2U816V60KHypVzhkk1D+nq6X23dXCRc2ULTZ72G-hjPwxw@mail.gmail.com>

On Thu, 3 Dec 2020 at 14:12, Shaozhong SHI <shishaozhong at gmail.com> wrote:
>
> We have been running Jupyter Notebook processes, which take long time to
> run.
>
> We use nbconvert to run these in commandline.  Nbconvert only writes output
> into a file at the end.
>
> We just wonder whether there is a way to observe the progress and printing
> messages when nbconvert is running.

If you're under linux, you can use `tail -f FILE` in the command line.

From pbryan at anode.ca  Thu Dec  3 01:37:09 2020
From: pbryan at anode.ca (Paul Bryan)
Date: Wed, 02 Dec 2020 22:37:09 -0800
Subject: list[type, type, ...] ?!
Message-ID: <957ba706cf549a1e7f94dcbbbfcdd3b259e0b1ba.camel@anode.ca>

Using the typing.List generic alias, I can only specify a single type.
Example:

>>> typing.List[int]
typing.List[int]

When I try to specify additional types, it fails. Example:

>>> typing.List[int, int]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.9/typing.py", line 243, in inner
    return func(*args, **kwds)
  File "/usr/lib/python3.9/typing.py", line 775, in __getitem__
    _check_generic(self, params, self._nparams)
  File "/usr/lib/python3.9/typing.py", line 197, in _check_generic
    raise TypeError(f"Too {'many' if alen > elen else 'few'} parameters for {cls};"
TypeError: Too many parameters for typing.List; actual 2, expected 1

This makes sense to me. An item has one type, and we use Union if we
want variants. What's not making sense to me in Python 3.9: I can use
the built-in generic alias in list?in this manner, apparently
successfully:

>>> list[int, int]
list[int, int]

In fact, it appears I can specify an indeterminate number of types. Can
someone explain what this construct means? I suspect this will fail to
be interpreted by type validators, but wonder why it doesn't fail fast
when I express it.

Thanks,

Paul

From pbryan at anode.ca  Thu Dec  3 12:19:04 2020
From: pbryan at anode.ca (Paul Bryan)
Date: Thu, 03 Dec 2020 09:19:04 -0800
Subject: help(list[int]) =?UTF-8?Q?=E2=86=92?= TypeError
Message-ID: <29ce2c4e1e0c7421466280efa225d30ba6f4967a.camel@anode.ca>

Is this the correct behavior?

Python 3.9.0 (default, Oct  7 2020, 23:09:01) 
[GCC 10.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> help(list[int])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.9/_sitebuiltins.py", line 103, in __call__
    return pydoc.help(*args, **kwds)
  File "/usr/lib/python3.9/pydoc.py", line 2001, in __call__
    self.help(request)
  File "/usr/lib/python3.9/pydoc.py", line 2060, in help
    else: doc(request, 'Help on %s:', output=self._output)
  File "/usr/lib/python3.9/pydoc.py", line 1779, in doc
    pager(render_doc(thing, title, forceload))
  File "/usr/lib/python3.9/pydoc.py", line 1772, in render_doc
    return title % desc + '\n\n' + renderer.document(object, name)
  File "/usr/lib/python3.9/pydoc.py", line 473, in document
    if inspect.isclass(object): return self.docclass(*args)
  File "/usr/lib/python3.9/pydoc.py", line 1343, in docclass
    (str(cls.__name__) for cls in type.__subclasses__(object)
TypeError: descriptor '__subclasses__' for 'type' objects doesn't apply to a 'types.GenericAlias' object
>>> 

I would have expected the output to the identical to help(list).

From greg.ewing at canterbury.ac.nz  Thu Dec  3 18:15:07 2020
From: greg.ewing at canterbury.ac.nz (Greg Ewing)
Date: Fri, 4 Dec 2020 12:15:07 +1300
Subject: list[type, type, ...] ?!
In-Reply-To: <mailman.288.1607020069.7193.python-list@python.org>
References: <957ba706cf549a1e7f94dcbbbfcdd3b259e0b1ba.camel@anode.ca>
 <mailman.288.1607020069.7193.python-list@python.org>
Message-ID: <i2t9rtF9cq8U1@mid.individual.net>

On 3/12/20 7:37 pm, Paul Bryan wrote:
>>>> list[int, int]
> list[int, int]
> 
> In fact, it appears I can specify an indeterminate number of types.

I think the built-in generic alias just provides the minimum
necessary to be able to write sometype[arg, ...]. It doesn't
know anything about the semantics with respect to particular
types -- that's left to the type checkers.

-- 
Greg

From greg.ewing at canterbury.ac.nz  Thu Dec  3 18:51:39 2020
From: greg.ewing at canterbury.ac.nz (Greg Ewing)
Date: Fri, 04 Dec 2020 12:51:39 +1300
Subject: list[type, type, ...] ?!
In-Reply-To: <f782ddc051355a10a6c319b6037d8f075b484ec3.camel@anode.ca>
References: <957ba706cf549a1e7f94dcbbbfcdd3b259e0b1ba.camel@anode.ca>
 <mailman.288.1607020069.7193.python-list@python.org>
 <i2t9rtF9cq8U1@mid.individual.net>
 <f782ddc051355a10a6c319b6037d8f075b484ec3.camel@anode.ca>
Message-ID: <951b40ec-b73a-e8d1-e2c0-09e483ad8c73@canterbury.ac.nz>

On 4/12/20 12:31 pm, Paul Bryan wrote:
> Would it make sense for list's __class_getitem__ 
> (GenericAlias?) to perform similar checking as 
> typing._SpecialGenericAlias (nparams)?

Maybe. It's a slippery slope -- how much of the typing module do we
want to drag into the core of the interpreter?

-- 
Greg

From pbryan at anode.ca  Thu Dec  3 18:31:30 2020
From: pbryan at anode.ca (Paul Bryan)
Date: Thu, 03 Dec 2020 15:31:30 -0800
Subject: list[type, type, ...] ?!
In-Reply-To: <i2t9rtF9cq8U1@mid.individual.net>
References: <957ba706cf549a1e7f94dcbbbfcdd3b259e0b1ba.camel@anode.ca>
 <mailman.288.1607020069.7193.python-list@python.org>
 <i2t9rtF9cq8U1@mid.individual.net>
Message-ID: <f782ddc051355a10a6c319b6037d8f075b484ec3.camel@anode.ca>

Thanks, Greg. Would it make sense for list's __class_getitem__
(GenericAlias?) to perform similar checking as
typing._SpecialGenericAlias (nparams)?

On Fri, 2020-12-04 at 12:15 +1300, Greg Ewing wrote:
> On 3/12/20 7:37 pm, Paul Bryan wrote:
> > > > > list[int, int]
> > list[int, int]
> > 
> > In fact, it appears I can specify an indeterminate number of types.
> 
> I think the built-in generic alias just provides the minimum
> necessary to be able to write sometype[arg, ...]. It doesn't
> know anything about the semantics with respect to particular
> types -- that's left to the type checkers.
> 
> -- 
> Greg


From noah-list at enabled.com  Fri Dec  4 09:15:33 2020
From: noah-list at enabled.com (Noah)
Date: Fri, 4 Dec 2020 06:15:33 -0800
Subject: [osx] dyld: Library not loaded:
 /usr/local/Cellar/python@3.8/3.8.3_1/Frameworks/Python.framework/Versions/3.8/Python
Message-ID: <c68463ac-d38f-c909-1815-7dc524c59f53@enabled.com>

Hi there,

Anybody know how to fix this issue on a mac?

? /usr/local/bin/python
dyld: Library not loaded: 
/usr/local/Cellar/python at 3.8/3.8.3_1/Frameworks/Python.framework/Versions/3.8/Python
   Referenced from: /usr/local/bin/python
   Reason: image not found
[1]    32209 abort      /usr/local/bin/python

Cheers

From julio at diegidio.name  Fri Dec  4 10:07:50 2020
From: julio at diegidio.name (Julio Di Egidio)
Date: Fri, 4 Dec 2020 07:07:50 -0800 (PST)
Subject: =?UTF-8?B?UmU6IGhlbHAobGlzdFtpbnRdKSDihpIgVHlwZUVycm9y?=
In-Reply-To: <mailman.289.1607020070.7193.python-list@python.org>
References: <29ce2c4e1e0c7421466280efa225d30ba6f4967a.camel@anode.ca>
 <mailman.289.1607020070.7193.python-list@python.org>
Message-ID: <b90a58ba-40f4-4444-9fcf-5dbb43777cfcn@googlegroups.com>

On Thursday, 3 December 2020 at 19:28:19 UTC+1, Paul Bryan wrote:
> Is this the correct behavior? 
> 
> Python 3.9.0 (default, Oct 7 2020, 23:09:01) 
> [GCC 10.2.0] on linux 
> Type "help", "copyright", "credits" or "license" for more information. 
> >>> help(list[int]) 
> Traceback (most recent call last): 
> File "<stdin>", line 1, in <module> 
> File "/usr/lib/python3.9/_sitebuiltins.py", line 103, in __call__ 
> return pydoc.help(*args, **kwds) 
> File "/usr/lib/python3.9/pydoc.py", line 2001, in __call__ 
> self.help(request) 
> File "/usr/lib/python3.9/pydoc.py", line 2060, in help 
> else: doc(request, 'Help on %s:', output=self._output) 
> File "/usr/lib/python3.9/pydoc.py", line 1779, in doc 
> pager(render_doc(thing, title, forceload)) 
> File "/usr/lib/python3.9/pydoc.py", line 1772, in render_doc 
> return title % desc + '\n\n' + renderer.document(object, name) 
> File "/usr/lib/python3.9/pydoc.py", line 473, in document 
> if inspect.isclass(object): return self.docclass(*args) 
> File "/usr/lib/python3.9/pydoc.py", line 1343, in docclass 
> (str(cls.__name__) for cls in type.__subclasses__(object) 
> TypeError: descriptor '__subclasses__' for 'type' objects doesn't apply to a 'types.GenericAlias' object 
> >>> 
> 
> I would have expected the output to the identical to help(list).

As I get it from the docs (*), these new generics still only work in type hinting contexts,
and I'd rather have expected a more useful error message: but, whether that is temporary
(possibly a plain bug, as in a forgotten case) or, instead, just "how things are", I wouldn't
know... might be a good question for Python developers.

(*) As in this one for a starter, but see also PEP 585:
"*In type annotations* you can now use ...", my emphasis.
<https://docs.python.org/3.9/whatsnew/3.9.html#type-hinting-generics-in-standard-collections>

Julio

From artott at gmail.com  Fri Dec  4 13:57:44 2020
From: artott at gmail.com (Arthur R. Ott)
Date: Fri, 04 Dec 2020 12:57:44 -0600
Subject: Fw: See example
References: <CAOB_2vjQ9tH6eeLKC=1tZbWgz5AuL9anEVO6iff+X4hBETrC1g@mail.gmail.com>
Message-ID: <ismljmop4h7a9qipuu6gbevn.1607108264120@gmail.com>

   Sent from my BlackBerry - the most secure mobile device

   From: artott at gmail.com
   Sent: December 4, 2020 10:40 AM
   To: python-list at python.org
   Subject: See example

   Microsoft Windows [Version 10.0.19042.630]
   (c) 2020 Microsoft Corporation. All rights reserved.
   I am sure you can help me....
   From the Windows10 command line, either in Admin mode or otherwise this is
   the error message I get. I want to program a Microprocessor?for the first
   time and I am already stuck. I have spent a lot of time?on both the
   internet and YouTube following different solutions. This entry worked two
   days ago and then the next day didn't. The "help" worksand the program
   appears to be operating normally.
   What can you suggest????
   C:\WINDOWS\system32>python
   Python 3.9.0a2 (tags/v3.9.0a2:6202d85, Dec 18 2019, 22:54:12) [MSC v.1916
   64 bit (AMD64)] on win32
   Type "help", "copyright", "credits" or "license" for more information.
   >>> pip --version
   Traceback (most recent call last):
   ? File "<stdin>", line 1, in <module>
   NameError: name 'pip' is not defined
   >>> python --version
   Traceback (most recent call last):
   ? File "<stdin>", line 1, in <module>
   NameError: name 'python' is not defined
   >>>
   Cheers
   ? ?? Art
   To God goes the glory for creation
   ?? Not to chance

From PythonList at DancesWithMice.info  Fri Dec  4 15:00:20 2020
From: PythonList at DancesWithMice.info (dn)
Date: Sat, 5 Dec 2020 09:00:20 +1300
Subject: Fw: See example
In-Reply-To: <ismljmop4h7a9qipuu6gbevn.1607108264120@gmail.com>
References: <CAOB_2vjQ9tH6eeLKC=1tZbWgz5AuL9anEVO6iff+X4hBETrC1g@mail.gmail.com>
 <ismljmop4h7a9qipuu6gbevn.1607108264120@gmail.com>
Message-ID: <23637178-3d81-31ea-396d-d3db1cdf50ef@DancesWithMice.info>

On 05/12/2020 07:57, Arthur R. Ott wrote:
...

>     Microsoft Windows [Version 10.0.19042.630]
>     (c) 2020 Microsoft Corporation. All rights reserved.
>     I am sure you can help me....
>     From the Windows10 command line, either in Admin mode or otherwise this is
>     the error message I get. I want to program a Microprocessor?for the first
>     time and I am already stuck. I have spent a lot of time?on both the
>     internet and YouTube following different solutions. This entry worked two
>     days ago and then the next day didn't. The "help" worksand the program
>     appears to be operating normally.
>     What can you suggest????
>     C:\WINDOWS\system32>python
>     Python 3.9.0a2 (tags/v3.9.0a2:6202d85, Dec 18 2019, 22:54:12) [MSC v.1916
>     64 bit (AMD64)] on win32
>     Type "help", "copyright", "credits" or "license" for more information.
>     >>> pip --version
>     Traceback (most recent call last):
>     ? File "<stdin>", line 1, in <module>
>     NameError: name 'pip' is not defined
>     >>> python --version
>     Traceback (most recent call last):
>     ? File "<stdin>", line 1, in <module>
>     NameError: name 'python' is not defined


Try the two commands from the command-line (rather than from within the 
Python interpreter/REPL).
-- 
Regards =dn

From pbryan at anode.ca  Fri Dec  4 15:09:21 2020
From: pbryan at anode.ca (Paul Bryan)
Date: Fri, 04 Dec 2020 12:09:21 -0800
Subject: help(list[int]) =?UTF-8?Q?=E2=86=92?= TypeError
In-Reply-To: <b90a58ba-40f4-4444-9fcf-5dbb43777cfcn@googlegroups.com>
References: <29ce2c4e1e0c7421466280efa225d30ba6f4967a.camel@anode.ca>
 <mailman.289.1607020070.7193.python-list@python.org>
 <b90a58ba-40f4-4444-9fcf-5dbb43777cfcn@googlegroups.com>
Message-ID: <861bba5dfe981701e59b97571e1dff14f9f76b08.camel@anode.ca>

Thanks, will bring it to the dev list.

On Fri, 2020-12-04 at 07:07 -0800, Julio Di Egidio wrote:
> On Thursday, 3 December 2020 at 19:28:19 UTC+1, Paul Bryan wrote:
> > Is this the correct behavior? 
> > 
> > Python 3.9.0 (default, Oct 7 2020, 23:09:01) 
> > [GCC 10.2.0] on linux 
> > Type "help", "copyright", "credits" or "license" for more
> > information. 
> > > > > help(list[int]) 
> > Traceback (most recent call last): 
> > File "<stdin>", line 1, in <module> 
> > File "/usr/lib/python3.9/_sitebuiltins.py", line 103, in __call__ 
> > return pydoc.help(*args, **kwds) 
> > File "/usr/lib/python3.9/pydoc.py", line 2001, in __call__ 
> > self.help(request) 
> > File "/usr/lib/python3.9/pydoc.py", line 2060, in help 
> > else: doc(request, 'Help on %s:', output=self._output) 
> > File "/usr/lib/python3.9/pydoc.py", line 1779, in doc 
> > pager(render_doc(thing, title, forceload)) 
> > File "/usr/lib/python3.9/pydoc.py", line 1772, in render_doc 
> > return title % desc + '\n\n' + renderer.document(object, name) 
> > File "/usr/lib/python3.9/pydoc.py", line 473, in document 
> > if inspect.isclass(object): return self.docclass(*args) 
> > File "/usr/lib/python3.9/pydoc.py", line 1343, in docclass 
> > (str(cls.__name__) for cls in type.__subclasses__(object) 
> > TypeError: descriptor '__subclasses__' for 'type' objects doesn't
> > apply to a 'types.GenericAlias' object 
> > > > > 
> > 
> > I would have expected the output to the identical to help(list).
> 
> As I get it from the docs (*), these new generics still only work in
> type hinting contexts,
> and I'd rather have expected a more useful error message: but,
> whether that is temporary
> (possibly a plain bug, as in a forgotten case) or, instead, just "how
> things are", I wouldn't
> know... might be a good question for Python developers.
> 
> (*) As in this one for a starter, but see also PEP 585:
> "*In type annotations* you can now use ...", my emphasis.
> <https://docs.python.org/3.9/whatsnew/3.9.html#type-hinting-generics-in-standard-collections
> >
> 
> Julio


From drsalists at gmail.com  Fri Dec  4 15:17:03 2020
From: drsalists at gmail.com (Dan Stromberg)
Date: Fri, 4 Dec 2020 12:17:03 -0800
Subject: Fw: See example
In-Reply-To: <23637178-3d81-31ea-396d-d3db1cdf50ef@DancesWithMice.info>
References: <CAOB_2vjQ9tH6eeLKC=1tZbWgz5AuL9anEVO6iff+X4hBETrC1g@mail.gmail.com>
 <ismljmop4h7a9qipuu6gbevn.1607108264120@gmail.com>
 <23637178-3d81-31ea-396d-d3db1cdf50ef@DancesWithMice.info>
Message-ID: <CAGGBd_qd0=JP2qxAjAW47-EMv_iqNyy69xcPpwv119_020TFyA@mail.gmail.com>

On Fri, Dec 4, 2020 at 12:01 PM dn via Python-list <python-list at python.org>
wrote:

> On 05/12/2020 07:57, Arthur R. Ott wrote:
> ...
>
> >     Microsoft Windows [Version 10.0.19042.630]
> >     (c) 2020 Microsoft Corporation. All rights reserved.
> >     I am sure you can help me....
> >     From the Windows10 command line, either in Admin mode or otherwise
> this is
> >     the error message I get. I want to program a Microprocessor for the
> first
> >     time and I am already stuck. I have spent a lot of time on both the
> >     internet and YouTube following different solutions. This entry
> worked two
> >     days ago and then the next day didn't. The "help" worksand the
> program
> >     appears to be operating normally.
> >     What can you suggest????
> >     C:\WINDOWS\system32>python
> >     Python 3.9.0a2 (tags/v3.9.0a2:6202d85, Dec 18 2019, 22:54:12) [MSC
> v.1916
> >     64 bit (AMD64)] on win32
> >     Type "help", "copyright", "credits" or "license" for more
> information.
> >     >>> pip --version
> >     Traceback (most recent call last):
> >       File "<stdin>", line 1, in <module>
> >     NameError: name 'pip' is not defined
> >     >>> python --version
> >     Traceback (most recent call last):
> >       File "<stdin>", line 1, in <module>
> >     NameError: name 'python' is not defined
>
>
> Try the two commands from the command-line (rather than from within the
> Python interpreter/REPL).
>

IOW, run pip or python from a command.com or powershell or cygwin bash.

From mats at wichmann.us  Fri Dec  4 19:21:51 2020
From: mats at wichmann.us (Mats Wichmann)
Date: Fri, 4 Dec 2020 17:21:51 -0700
Subject: [osx] dyld: Library not loaded:
 /usr/local/Cellar/python@3.8/3.8.3_1/Frameworks/Python.framework/Versions/3.8/Python
In-Reply-To: <c68463ac-d38f-c909-1815-7dc524c59f53@enabled.com>
References: <c68463ac-d38f-c909-1815-7dc524c59f53@enabled.com>
Message-ID: <3633067d-5613-c9ef-9b0e-55b1373a3e88@wichmann.us>

On 12/4/20 7:15 AM, Noah wrote:
> Hi there,
> 
> Anybody know how to fix this issue on a mac?
> 
> ? /usr/local/bin/python
> dyld: Library not loaded: 
> /usr/local/Cellar/python at 3.8/3.8.3_1/Frameworks/Python.framework/Versions/3.8/Python 
> 
>  ? Referenced from: /usr/local/bin/python
>  ? Reason: image not found
> [1]??? 32209 abort????? /usr/local/bin/python

Looks like you're using Python installed via Homebrew ('Cellar' being 
the hint), perhaps hit up that project for ideas?  It looks like the 
install is inconsistent somehow.



From PythonList at DancesWithMice.info  Fri Dec  4 20:37:02 2020
From: PythonList at DancesWithMice.info (DL Neil)
Date: Sat, 5 Dec 2020 14:37:02 +1300
Subject: Fw: See example
In-Reply-To: <CAGGBd_qd0=JP2qxAjAW47-EMv_iqNyy69xcPpwv119_020TFyA@mail.gmail.com>
References: <CAOB_2vjQ9tH6eeLKC=1tZbWgz5AuL9anEVO6iff+X4hBETrC1g@mail.gmail.com>
 <ismljmop4h7a9qipuu6gbevn.1607108264120@gmail.com>
 <23637178-3d81-31ea-396d-d3db1cdf50ef@DancesWithMice.info>
 <CAGGBd_qd0=JP2qxAjAW47-EMv_iqNyy69xcPpwv119_020TFyA@mail.gmail.com>
Message-ID: <b9372c8e-e38c-7792-bdef-fa5fd78d5eb5@DancesWithMice.info>

On 05/12/2020 09:17, Dan Stromberg wrote:
> 
> On Fri, Dec 4, 2020 at 12:01 PM dn via Python-list 
> <python-list at python.org <mailto:python-list at python.org>> wrote:
> 
>     On 05/12/2020 07:57, Arthur R. Ott wrote:
>     ...
> 
>      >? ? ?Microsoft Windows [Version 10.0.19042.630]
>      >? ? ?(c) 2020 Microsoft Corporation. All rights reserved.
>      >? ? ?I am sure you can help me....
>      >? ? ?From the Windows10 command line, either in Admin mode or
>     otherwise this is
>      >? ? ?the error message I get. I want to program a
>     Microprocessor?for the first
>      >? ? ?time and I am already stuck. I have spent a lot of time?on
>     both the
>      >? ? ?internet and YouTube following different solutions. This
>     entry worked two
>      >? ? ?days ago and then the next day didn't. The "help" worksand
>     the program
>      >? ? ?appears to be operating normally.
>      >? ? ?What can you suggest????
>      >? ? ?C:\WINDOWS\system32>python
>      >? ? ?Python 3.9.0a2 (tags/v3.9.0a2:6202d85, Dec 18 2019, 22:54:12)
>     [MSC v.1916
>      >? ? ?64 bit (AMD64)] on win32
>      >? ? ?Type "help", "copyright", "credits" or "license" for more
>     information.
>      >? ? ?>>> pip --version
>      >? ? ?Traceback (most recent call last):
>      >? ? ?? File "<stdin>", line 1, in <module>
>      >? ? ?NameError: name 'pip' is not defined
>      >? ? ?>>> python --version
>      >? ? ?Traceback (most recent call last):
>      >? ? ?? File "<stdin>", line 1, in <module>
>      >? ? ?NameError: name 'python' is not defined
> 
> 
>     Try the two commands from the command-line (rather than from within the
>     Python interpreter/REPL).
> 
> 
> IOW, run pip or python from a command.com <http://command.com> or 
> powershell or cygwin bash.


Yes, thank you @Dan, I don't use MS-Win!

The fact that the two (version) commands are being typed in response to 
a ">>>" prompt indicates that Python is already running, yet they are 
BASH/Windows command-line/DOS-box commands!
-- 
Regards =dn

From bdorestand at example.com  Sat Dec  5 12:16:11 2020
From: bdorestand at example.com (Boris Dorestand)
Date: Sat, 05 Dec 2020 14:16:11 -0300
Subject: how to plot the FFT of a list of values
Message-ID: <86r1o4kwbo.fsf@example.com>

I have 16 values of the period sequence 1, 2, 4, 8, 1, 2, 4, 8, ...  I
compute its fourier transform using

>>> from scipy import fft, ifft
>>> x = [1,2,4,8,1,2,4,8]
>>> fft(x)
array([ 30. +0.j,   0. +0.j,  -6.+12.j,   0. +0.j, -10. +0.j,   0. +0.j,
        -6.-12.j,   0. +0.j])

Now how can I plot these values?  I would like to plot 16 values.  What
do I need to do here?  Can you show an example?

From drsalists at gmail.com  Sat Dec  5 13:07:30 2020
From: drsalists at gmail.com (Dan Stromberg)
Date: Sat, 5 Dec 2020 10:07:30 -0800
Subject: how to plot the FFT of a list of values
In-Reply-To: <86r1o4kwbo.fsf@example.com>
References: <86r1o4kwbo.fsf@example.com>
Message-ID: <CAGGBd_oLhkQqXdQBpqO0uKvqMEjug1sn=spL1HY0anb=2incOg@mail.gmail.com>

On Sat, Dec 5, 2020 at 9:20 AM Boris Dorestand <bdorestand at example.com>
wrote:

> I have 16 values of the period sequence 1, 2, 4, 8, 1, 2, 4, 8, ...  I
> compute its fourier transform using
>
> >>> from scipy import fft, ifft
> >>> x = [1,2,4,8,1,2,4,8]
> >>> fft(x)
> array([ 30. +0.j,   0. +0.j,  -6.+12.j,   0. +0.j, -10. +0.j,   0. +0.j,
>         -6.-12.j,   0. +0.j])
>
> Now how can I plot these values?  I would like to plot 16 values.  What
> do I need to do here?  Can you show an example?
>

Maybe
https://stackoverflow.com/questions/17445720/how-to-plot-complex-numbers-argand-diagram-using-matplotlib
?

From p_d_a_s_i_l_v_a_ns at nonetnoaddress.pt  Sat Dec  5 13:56:46 2020
From: p_d_a_s_i_l_v_a_ns at nonetnoaddress.pt (Paulo da Silva)
Date: Sat, 5 Dec 2020 18:56:46 +0000
Subject: Learning tkinter - a grid problem
Message-ID: <rqgl5d$8ia$1@gioia.aioe.org>

Hi!

Why this example does not work?

------------------
from tkinter import *

root=Tk()
root.geometry("400x200")
S=Scrollbar(root)
T=Text(root)
T.grid(row=0,column=0)
S.grid(row=0,column=1)
S.config(command=T.yview)
T.config(yscrollcommand=S.set)
txt="""This is a very big text
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Last line
"""
T.insert(END,txt)
mainloop()
---------------------

I would like it to work more or less like this

---------------------
from tkinter import *

root=Tk()
root.geometry("400x200")
S=Scrollbar(root)
T=Text(root)
S.pack(side=RIGHT,fill=Y)
T.pack(side=LEFT,fill=Y)
S.config(command=T.yview)
T.config(yscrollcommand=S.set)
txt="""This is a very big text
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Last line
"""
T.insert(END,txt)
mainloop()
---------------------

Thanks for any help
Paulo


From python at mrabarnett.plus.com  Sat Dec  5 15:20:11 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Sat, 5 Dec 2020 20:20:11 +0000
Subject: Learning tkinter - a grid problem
In-Reply-To: <rqgl5d$8ia$1@gioia.aioe.org>
References: <rqgl5d$8ia$1@gioia.aioe.org>
Message-ID: <352abde5-7228-f123-e6c6-340a8cd90fe1@mrabarnett.plus.com>

On 2020-12-05 18:56, Paulo da Silva wrote:
> Hi!
> 
> Why this example does not work?
> 
There are a few bits of configuration missing:

> ------------------
> from tkinter import *
> 
> root=Tk()
> root.geometry("400x200")

Add:

root.grid_rowconfigure(0, weight=1)
root.grid_columnconfigure(0, weight=1)
root.grid_columnconfigure(1, weight=0)

> S=Scrollbar(root)
> T=Text(root)
> T.grid(row=0,column=0)
> S.grid(row=0,column=1)

Change to:

T.grid(row=0, column=0, sticky=NSEW)
S.grid(row=0, column=1, sticky=NS)

> S.config(command=T.yview)
> T.config(yscrollcommand=S.set)
> txt="""This is a very big text
> -
> -
> -
> -
> -
> -
> -
> -
> -
> -
> -
> -
> -
> -
> -
> -
> Last line
> """
> T.insert(END,txt)
> mainloop()
> ---------------------
> 
[snip]

From p_d_a_s_i_l_v_a_ns at nonetnoaddress.pt  Sat Dec  5 15:45:12 2020
From: p_d_a_s_i_l_v_a_ns at nonetnoaddress.pt (Paulo da Silva)
Date: Sat, 5 Dec 2020 20:45:12 +0000
Subject: Learning tkinter - a grid problem
References: <rqgl5d$8ia$1@gioia.aioe.org>
 <352abde5-7228-f123-e6c6-340a8cd90fe1@mrabarnett.plus.com>
 <mailman.300.1607199622.7193.python-list@python.org>
Message-ID: <rqgrgn$171b$1@gioia.aioe.org>

?s 20:20 de 05/12/20, MRAB escreveu:
> On 2020-12-05 18:56, Paulo da Silva wrote:
>> Hi!
>>
>> Why this example does not work?
>>
> There are a few bits of configuration missing:
> 
>> ------------------
>> from tkinter import *
>>
>> root=Tk()
>> root.geometry("400x200")
> 
> Add:
> 
> root.grid_rowconfigure(0, weight=1)
> root.grid_columnconfigure(0, weight=1)
> root.grid_columnconfigure(1, weight=0)
> 
>> S=Scrollbar(root)
>> T=Text(root)
>> T.grid(row=0,column=0)
>> S.grid(row=0,column=1)
> 
> Change to:
> 
> T.grid(row=0, column=0, sticky=NSEW)
> S.grid(row=0, column=1, sticky=NS)
> 
>> S.config(command=T.yview)
>> T.config(yscrollcommand=S.set)
>> txt="""This is a very big text
>> -

Ok, thank you.

From auriocus at gmx.de  Sat Dec  5 17:08:45 2020
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Sat, 5 Dec 2020 23:08:45 +0100
Subject: how to plot the FFT of a list of values
In-Reply-To: <86r1o4kwbo.fsf@example.com>
References: <86r1o4kwbo.fsf@example.com>
Message-ID: <rqh0dd$nv7$1@dont-email.me>

Am 05.12.20 um 18:16 schrieb Boris Dorestand:
> I have 16 values of the period sequence 1, 2, 4, 8, 1, 2, 4, 8, ...  I
> compute its fourier transform using
> 
>>>> from scipy import fft, ifft
>>>> x = [1,2,4,8,1,2,4,8]
>>>> fft(x)
> array([ 30. +0.j,   0. +0.j,  -6.+12.j,   0. +0.j, -10. +0.j,   0. +0.j,
>          -6.-12.j,   0. +0.j])
> 
> Now how can I plot these values?  I would like to plot 16 values.  What
> do I need to do here?  Can you show an example?


Usually, for the FFT of real input data, you plot only the magnitude or 
square of the complex array, and usually on a logscale. So:

import pylab
import numpy as np

fx = fft(x)

pylab.semilogy(np.abs(fx))
pylab.show()



	Christian




From sjeik_appie at hotmail.com  Sat Dec  5 17:30:25 2020
From: sjeik_appie at hotmail.com (sjeik_appie at hotmail.com)
Date: Sat, 05 Dec 2020 23:30:25 +0100
Subject: Bot
In-Reply-To: <CAFnUUM=r0xYjoKgBFK8WoSzufGo05b_F5mBduyu=T7oes-oytQ@mail.gmail.com>
Message-ID: <DBAP193MB079398C6005280CE4988725283F00@DBAP193MB0793.EURP193.PROD.OUTLOOK.COM>

   Try Selenium (preferred) or Mechanize. I recently used Selenium with
   Chrome for automated unittests of a web app, including a login screen. You
   could fire up the selenium script in a cron job at the desired time.
   On 1 Dec 2020 09:53, ?lvaro d'Ors <alvarodorsnestares at gmail.com> wrote:

     Hi guys, I'm new here, can anyone help me built a bot than can input
     data
     in a website?
     This is not for spam purposes, I just need to reserve a place in the
     library at the university but they are completed in a matter of minutes
     and
     I can't waste time "camping" the website. Thank you

     Nestares D. ?lvaro
     --
     https://mail.python.org/mailman/listinfo/python-list

From sjeik_appie at hotmail.com  Sat Dec  5 17:42:11 2020
From: sjeik_appie at hotmail.com (sjeik_appie at hotmail.com)
Date: Sat, 05 Dec 2020 23:42:11 +0100
Subject: Regarding Regex timeout behavior to minimize CPU consumption
In-Reply-To: <CAPGjASGV1wzS_3h2vdW_3JhpzCaBh6k4pZMccJ8gHE787u7gGA@mail.gmail.com>
Message-ID: <DBAP193MB079391CA17AF6D2A6F3DD67583F00@DBAP193MB0793.EURP193.PROD.OUTLOOK.COM>

   Hi,
   Timeout: no idea. But check out re.compile and re.iterfind as they might
   speed things up. I often compile a regex once upon import, then use it in
   functions
   On 27 Nov 2020 13:33, Shahique Khan <shahiquzzama at gmail.com> wrote:

     Hi Team,

     I have noticed if our regex sometimes does not give a result and on that
     time regex took more time in returning response (empty response).

     My Question is can we set a timeout parameter (in seconds/millisecond)
     with
     re.find or anywhere in code to avoid CPU consumption if regex takes more
     time in execution.

     Below is the example, which take more time in execution: (in this case
     can
     we set timeout to kill the execution to avoid CPU consumption)

     regex = r'data-stid="section-room-list"[\s\S]*?>\s*([\s\S]*?)\s*' \
     ???????
     r'(?:class\s*=\s*"\s*sticky-book-now\s*"|</ul>\s*</section>|id\s*=\s*"Location")'
     rooms_blocks_to_be_replace = re.findall(regex, html_template)

     Please help me, I will be very thankful for this.

     Thanks,
     --
     https://mail.python.org/mailman/listinfo/python-list

From hjp-python at hjp.at  Sat Dec  5 18:34:13 2020
From: hjp-python at hjp.at (Peter J. Holzer)
Date: Sun, 6 Dec 2020 00:34:13 +0100
Subject: Regarding Regex timeout behavior to minimize CPU consumption
In-Reply-To: <DBAP193MB079391CA17AF6D2A6F3DD67583F00@DBAP193MB0793.EURP193.PROD.OUTLOOK.COM>
References: <CAPGjASGV1wzS_3h2vdW_3JhpzCaBh6k4pZMccJ8gHE787u7gGA@mail.gmail.com>
 <DBAP193MB079391CA17AF6D2A6F3DD67583F00@DBAP193MB0793.EURP193.PROD.OUTLOOK.COM>
Message-ID: <20201205233413.GB29541@hjp.at>

On 2020-12-05 23:42:11 +0100, sjeik_appie at hotmail.com wrote:
>    Timeout: no idea. But check out re.compile and re.iterfind as they might
>    speed things up.

I doubt that compiling regular expressions helps the OP much. Compiled
regular expressions are cached, but more importantly, if a match takes
long enough that specifying a timeout is useful, the time is almost
certainly not spent compiling, but matching - most likely backtracking
from lots of promising but ultimately unsuccessful partial matches.

>      regex = r'data-stid="section-room-list"[\s\S]*?>\s*([\s\S]*?)\s*' \
>      ???????
>      r'(?:class\s*=\s*"\s*sticky-book-now\s*"|</ul>\s*</section>|id\s*=\s*"Location")'
>      rooms_blocks_to_be_replace = re.findall(regex, html_template)

This part:

    \s*([\s\S]*?)\s*'

looks dangerous from a performance point of view. If that can be
rewritten with less potential for backtracking, it might help.

Generally, it should be possible to implement a timeout for any
operation by either scheduling an alarm with signal.alarm or by
executing the operation in a separate thread and killing the thread if
it takes too long.

        hp

-- 
   _  | Peter J. Holzer    | Story must make more sense than reality.
|_|_) |                    |
| |   | hjp at hjp.at         |    -- Charles Stross, "Creative writing
__/   | http://www.hjp.at/ |       challenge!"
-------------- next part --------------
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From nulla.epistola at web.de  Sun Dec  6 03:11:51 2020
From: nulla.epistola at web.de (Sibylle Koczian)
Date: Sun, 6 Dec 2020 09:11:51 +0100
Subject: Learning tkinter - a grid problem
In-Reply-To: <rqgl5d$8ia$1@gioia.aioe.org>
References: <rqgl5d$8ia$1@gioia.aioe.org>
Message-ID: <c245040c-1c92-9f0a-6f35-74313e417c6a@web.de>

Am 05.12.2020 um 19:56 schrieb Paulo da Silva:
> Hi!
>
> Why this example does not work?
>
> ------------------
> from tkinter import *
>
> root=Tk()
> root.geometry("400x200")
> S=Scrollbar(root)
> T=Text(root)
...
> mainloop()
> ---------------------
>

Shouldn't that be

root.mainloop()

?



From nulla.epistola at web.de  Sun Dec  6 03:11:51 2020
From: nulla.epistola at web.de (Sibylle Koczian)
Date: Sun, 6 Dec 2020 09:11:51 +0100
Subject: Learning tkinter - a grid problem
In-Reply-To: <rqgl5d$8ia$1@gioia.aioe.org>
References: <rqgl5d$8ia$1@gioia.aioe.org>
Message-ID: <c245040c-1c92-9f0a-6f35-74313e417c6a@web.de>

Am 05.12.2020 um 19:56 schrieb Paulo da Silva:
> Hi!
> 
> Why this example does not work?
> 
> ------------------
> from tkinter import *
> 
> root=Tk()
> root.geometry("400x200")
> S=Scrollbar(root)
> T=Text(root)
...
> mainloop()
> ---------------------
> 

Shouldn't that be

root.mainloop()

?




From python at mrabarnett.plus.com  Sun Dec  6 09:19:19 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Sun, 6 Dec 2020 14:19:19 +0000
Subject: Learning tkinter - a grid problem
In-Reply-To: <c245040c-1c92-9f0a-6f35-74313e417c6a@web.de>
References: <rqgl5d$8ia$1@gioia.aioe.org>
 <c245040c-1c92-9f0a-6f35-74313e417c6a@web.de>
Message-ID: <b282687a-fe5b-020d-3598-c4df912334d8@mrabarnett.plus.com>

On 2020-12-06 08:11, Sibylle Koczian wrote:
> Am 05.12.2020 um 19:56 schrieb Paulo da Silva:
>> Hi!
>>
>> Why this example does not work?
>>
>> ------------------
>> from tkinter import *
>>
>> root=Tk()
>> root.geometry("400x200")
>> S=Scrollbar(root)
>> T=Text(root)
> ...
>> mainloop()
>> ---------------------
>>
> 
> Shouldn't that be
> 
> root.mainloop()
> 
> ?
> 
The function 'mainloop' calls the 'mainloop' method of the root Tk 
window created by Tk(), so it does work as-is.

From nulla.epistola at web.de  Sun Dec  6 13:16:55 2020
From: nulla.epistola at web.de (Sibylle Koczian)
Date: Sun, 6 Dec 2020 19:16:55 +0100
Subject: Learning tkinter - a grid problem
In-Reply-To: <b282687a-fe5b-020d-3598-c4df912334d8@mrabarnett.plus.com>
References: <rqgl5d$8ia$1@gioia.aioe.org>
 <c245040c-1c92-9f0a-6f35-74313e417c6a@web.de>
 <b282687a-fe5b-020d-3598-c4df912334d8@mrabarnett.plus.com>
Message-ID: <8ccace6b-33fe-e0ad-1c90-bb138892e6bb@web.de>

Am 06.12.2020 um 15:19 schrieb MRAB:
> On 2020-12-06 08:11, Sibylle Koczian wrote:
>> Am 05.12.2020 um 19:56 schrieb Paulo da Silva:
>>> Hi!
>>>
>>> Why this example does not work?
>>>
>>> ------------------
>>> from tkinter import *
>>>
>>> root=Tk()
>>> root.geometry("400x200")
>>> S=Scrollbar(root)
>>> T=Text(root)
>> ...
>>> mainloop()
>>> ---------------------
>>>
>>
>> Shouldn't that be
>>
>> root.mainloop()
>>
>> ?
>>
> The function 'mainloop' calls the 'mainloop' method of the root Tk
> window created by Tk(), so it does work as-is.

Didn't know that, thank you!

From nulla.epistola at web.de  Sun Dec  6 13:16:55 2020
From: nulla.epistola at web.de (Sibylle Koczian)
Date: Sun, 6 Dec 2020 19:16:55 +0100
Subject: Learning tkinter - a grid problem
In-Reply-To: <b282687a-fe5b-020d-3598-c4df912334d8@mrabarnett.plus.com>
References: <rqgl5d$8ia$1@gioia.aioe.org>
 <c245040c-1c92-9f0a-6f35-74313e417c6a@web.de>
 <b282687a-fe5b-020d-3598-c4df912334d8@mrabarnett.plus.com>
Message-ID: <8ccace6b-33fe-e0ad-1c90-bb138892e6bb@web.de>

Am 06.12.2020 um 15:19 schrieb MRAB:
> On 2020-12-06 08:11, Sibylle Koczian wrote:
>> Am 05.12.2020 um 19:56 schrieb Paulo da Silva:
>>> Hi!
>>>
>>> Why this example does not work?
>>>
>>> ------------------
>>> from tkinter import *
>>>
>>> root=Tk()
>>> root.geometry("400x200")
>>> S=Scrollbar(root)
>>> T=Text(root)
>> ...
>>> mainloop()
>>> ---------------------
>>>
>>
>> Shouldn't that be
>>
>> root.mainloop()
>>
>> ?
>>
> The function 'mainloop' calls the 'mainloop' method of the root Tk 
> window created by Tk(), so it does work as-is.

Didn't know that, thank you!


From tjreedy at udel.edu  Sun Dec  6 05:59:01 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 6 Dec 2020 05:59:01 -0500
Subject: Learning tkinter - a grid problem
In-Reply-To: <c245040c-1c92-9f0a-6f35-74313e417c6a@web.de>
References: <rqgl5d$8ia$1@gioia.aioe.org>
 <c245040c-1c92-9f0a-6f35-74313e417c6a@web.de>
Message-ID: <rqidhm$i72$1@ciao.gmane.io>

On 12/6/2020 3:11 AM, Sibylle Koczian wrote:
> Am 05.12.2020 um 19:56 schrieb Paulo da Silva:

>> Why this example does not work?
>> ------------------
>> from tkinter import *
>>
>> root=Tk()
>> root.geometry("400x200")
>> S=Scrollbar(root)
>> T=Text(root)
> ...
>> mainloop()

> Shouldn't that be
> root.mainloop()
> ?

Yes.  The * import does not turn method into module functions.

-- 
Terry Jan Reedy


From baroldonfire at yahoo.com  Sat Dec  5 13:41:16 2020
From: baroldonfire at yahoo.com (Barry Fitzgerald)
Date: Sat, 5 Dec 2020 13:41:16 -0500
Subject: Error
References: <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61.ref@yahoo.com>
Message-ID: <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61@yahoo.com>

Good day,"

I purchased a book for my son and followed the directions to a T. (Coding Games in Python)
Whenever I got to the point of of moving the "hello" file over to pgzrun is where my trouble began.
Its not finding a path because I'm getting this "pgzrun is not recognized as an internal or external command".

I've uninstall reinstall and tried to trouble shoot offline.  I' believe its a "path" issue but that is a little over my head.  At least this is what I've read.  Yes I selected all users and the variables options on custom install.

Any Suggestions?



From PythonList at DancesWithMice.info  Sun Dec  6 15:39:09 2020
From: PythonList at DancesWithMice.info (dn)
Date: Mon, 7 Dec 2020 09:39:09 +1300
Subject: Error
In-Reply-To: <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61@yahoo.com>
References: <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61.ref@yahoo.com>
 <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61@yahoo.com>
Message-ID: <8dbc7420-4603-59b8-b131-1735b0f1ebdf@DancesWithMice.info>

On 06/12/2020 07:41, Barry Fitzgerald via Python-list wrote:
> Good day,"
> 
> I purchased a book for my son and followed the directions to a T. (Coding Games in Python)
> Whenever I got to the point of of moving the "hello" file over to pgzrun is where my trouble began.
> Its not finding a path because I'm getting this "pgzrun is not recognized as an internal or external command".
> 
> I've uninstall reinstall and tried to trouble shoot offline.  I' believe its a "path" issue but that is a little over my head.  At least this is what I've read.  Yes I selected all users and the variables options on custom install.
> 
> Any Suggestions?


It would help to have some detail: OpSys, source of Python and pygame, 
editor/IDE in-use, how executing pygame zero, etc.

- please copy-paste relevant code and/or error messages.

else: https://duckduckgo.com/?q=pgzrun&ia=web

-- 
Regards =dn

From torriem at gmail.com  Sun Dec  6 17:32:01 2020
From: torriem at gmail.com (Michael Torrie)
Date: Sun, 6 Dec 2020 15:32:01 -0700
Subject: Error
In-Reply-To: <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61@yahoo.com>
References: <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61.ref@yahoo.com>
 <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61@yahoo.com>
Message-ID: <29e8366d-2ec6-7041-596d-c1aab30e22d5@gmail.com>

On 12/5/20 11:41 AM, Barry Fitzgerald via Python-list wrote:
> Good day,"
> 
> I purchased a book for my son and followed the directions to a T. (Coding Games in Python)
> Whenever I got to the point of of moving the "hello" file over to pgzrun is where my trouble began.
> Its not finding a path because I'm getting this "pgzrun is not recognized as an internal or external command".
> 
> I've uninstall reinstall and tried to trouble shoot offline.  I' believe its a "path" issue but that is a little over my head.  At least this is what I've read.  Yes I selected all users and the variables options on custom install.

I think you're referring to PyGame Zero.  Where did you download the
installer from?

From barry at barrys-emacs.org  Sun Dec  6 17:36:25 2020
From: barry at barrys-emacs.org (Barry)
Date: Sun, 6 Dec 2020 22:36:25 +0000
Subject: Regarding Regex timeout behavior to minimize CPU consumption
In-Reply-To: <20201205233413.GB29541@hjp.at>
References: <20201205233413.GB29541@hjp.at>
Message-ID: <2678A846-66D9-4A7E-8C4F-5B6D49163958@barrys-emacs.org>



> On 5 Dec 2020, at 23:44, Peter J. Holzer <hjp-python at hjp.at> wrote:
> 
> ?On 2020-12-05 23:42:11 +0100, sjeik_appie at hotmail.com wrote:
>>   Timeout: no idea. But check out re.compile and re.iterfind as they might
>>   speed things up.
> 
> I doubt that compiling regular expressions helps the OP much. Compiled
> regular expressions are cached, but more importantly, if a match takes
> long enough that specifying a timeout is useful, the time is almost
> certainly not spent compiling, but matching - most likely backtracking
> from lots of promising but ultimately unsuccessful partial matches.
> 
>>     regex = r'data-stid="section-room-list"[\s\S]*?>\s*([\s\S]*?)\s*' \
>>            
>>     r'(?:class\s*=\s*"\s*sticky-book-now\s*"|</ul>\s*</section>|id\s*=\s*"Location")'
>>     rooms_blocks_to_be_replace = re.findall(regex, html_template)
> 
> This part:
> 
>    \s*([\s\S]*?)\s*'
> 
> looks dangerous from a performance point of view. If that can be
> rewritten with less potential for backtracking, it might help.
> 
> Generally, it should be possible to implement a timeout for any
> operation by either scheduling an alarm with signal.alarm or by
> executing the operation in a separate thread and killing the thread if
> it takes too long.

I think that python ignores signals until the coeval loop is entered.
And since the re.match will block that is not going to happen.

Killing threads is not safe and if your OS allows it then you end up with the internal state of python messed up.

To implement this I think requires the re code to implement the timeout.

Better is for the OP to fix the re to not back track so much or to work on the
input string in chunks.

Barry

> 
>        hp
> 
> -- 
>   _  | Peter J. Holzer    | Story must make more sense than reality.
> |_|_) |                    |
> | |   | hjp at hjp.at         |    -- Charles Stross, "Creative writing
> __/   | http://www.hjp.at/ |       challenge!"
> -- 
> https://mail.python.org/mailman/listinfo/python-list


From torriem at gmail.com  Sun Dec  6 18:09:42 2020
From: torriem at gmail.com (Michael Torrie)
Date: Sun, 6 Dec 2020 16:09:42 -0700
Subject: Error
In-Reply-To: <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61@yahoo.com>
References: <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61.ref@yahoo.com>
 <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61@yahoo.com>
Message-ID: <cd09cefe-2564-2f1e-1f0e-4615810a7d14@gmail.com>

On 12/5/20 11:41 AM, Barry Fitzgerald via Python-list wrote:
> Good day,"
> 
> I purchased a book for my son and followed the directions to a T.
> (Coding Games in Python) Whenever I got to the point of of moving the
> "hello" file over to pgzrun is where my trouble began. Its not
> finding a path because I'm getting this "pgzrun is not recognized as
> an internal or external command".
> 
> I've uninstall reinstall and tried to trouble shoot offline.  I'
> believe its a "path" issue but that is a little over my head.  At
> least this is what I've read.  Yes I selected all users and the
> variables options on custom install.
Looks to me like you have to do two things to get PyGame Zero going on
Windows.  First, install the latest stable Python 3 from python.org.  Be
sure to tell the installer to put Python in the system path so you can
get to it from the command prompt.

Second, from a command prompt, run:

py -m pip install pgzero

And then you must put the location pgzrun.exe in your path.  See below.

For example this is what you'd see:
C:\Users\torriem>py -m pip install pgzero
Collecting pgzero
  Using cached
https://files.pythonhosted.org/packages/48/e5/e5f14292373cb5fc7539aa01307b184c1e3c954d68945d8c44778669dd82/pgzero-1.2-py3-none-any.whl
Collecting numpy (from pgzero)
  Using cached
https://files.pythonhosted.org/packages/40/db/5060f18b0116f00ee73f8365efc9c95bd5496946290b0e7c97b6ee89dffe/numpy-1.19.4-cp38-cp38-win_amd64.whl
Collecting pygame<2.0,>=1.9.2 (from pgzero)
  Using cached
https://files.pythonhosted.org/packages/a8/1e/5da797179ce046decc7d6d57a9b1977218103ccfb099b959b7736aff5f73/pygame-1.9.6-cp38-cp38-win_amd64.whl
Installing collected packages: numpy, pygame, pgzero
  WARNING: The script f2py.exe is installed in
'C:\Users\torriem\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.8_qbz5n2kfra8p0\LocalCache\local-packages\Python38\Scripts'
which is not on PATH.
  Consider adding this directory to PATH or, if you prefer to suppress
this warning, use --no-warn-script-location.
  WARNING: The script pgzrun.exe is installed in
'C:\Users\torriem\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.8_qbz5n2kfra8p0\LocalCache\local-packages\Python38\Scripts'
which is not on PATH.
  Consider adding this directory to PATH or, if you prefer to suppress
this warning, use --no-warn-script-location.
Successfully installed numpy-1.19.4 pgzero-1.2 pygame-1.9.6
WARNING: You are using pip version 19.2.3, however version 20.3.1 is
available.
You should consider upgrading via the 'python -m pip install --upgrade
pip' command.

Note the WARNINGs about the scripts and path. You'll want to take that
directory (which will be different on your machine) and add that to the
path.  See
https://www.architectryan.com/2018/03/17/add-to-the-path-on-windows-10/
for an example of how to do that.

In my case, the path I need to add is
C:\Users\torriem\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.8_qbz5n2kfra8p0\LocalCache\local-packages\Python38\Scripts

After that, pgzrun should run as the book says it will.

From drsalists at gmail.com  Sun Dec  6 23:27:34 2020
From: drsalists at gmail.com (Dan Stromberg)
Date: Sun, 6 Dec 2020 20:27:34 -0800
Subject: Regarding Regex timeout behavior to minimize CPU consumption
In-Reply-To: <2678A846-66D9-4A7E-8C4F-5B6D49163958@barrys-emacs.org>
References: <20201205233413.GB29541@hjp.at>
 <2678A846-66D9-4A7E-8C4F-5B6D49163958@barrys-emacs.org>
Message-ID: <CAGGBd_qbQA8h7vGSE=B_n4UvKvo2_qkPssa7iKpptZsG8JwJGQ@mail.gmail.com>

On Sun, Dec 6, 2020 at 2:37 PM Barry <barry at barrys-emacs.org> wrote:

> > On 5 Dec 2020, at 23:44, Peter J. Holzer <hjp-python at hjp.at> wrote:
> >
> > ?On 2020-12-05 23:42:11 +0100, sjeik_appie at hotmail.com wrote:
> >>   Timeout: no idea. But check out re.compile and re.iterfind as they
> might
> >>   speed things up.
> >
> > I doubt that compiling regular expressions helps the OP much. Compiled
> > regular expressions are cached, but more importantly, if a match takes
> > long enough that specifying a timeout is useful, the time is almost
> > certainly not spent compiling, but matching - most likely backtracking
> > from lots of promising but ultimately unsuccessful partial matches.
> >
> >>     regex = r'data-stid="section-room-list"[\s\S]*?>\s*([\s\S]*?)\s*' \
> >>
> >>
>  r'(?:class\s*=\s*"\s*sticky-book-now\s*"|</ul>\s*</section>|id\s*=\s*"Location")'
> >>     rooms_blocks_to_be_replace = re.findall(regex, html_template)
> >
> > This part:
> >
> >    \s*([\s\S]*?)\s*'
> >
> > looks dangerous from a performance point of view. If that can be
> > rewritten with less potential for backtracking, it might help.
> >
> > Generally, it should be possible to implement a timeout for any
> > operation by either scheduling an alarm with signal.alarm or by
> > executing the operation in a separate thread and killing the thread if
> > it takes too long.
>
> I think that python ignores signals until the coeval loop is entered.
> And since the re.match will block that is not going to happen.
>
> Killing threads is not safe and if your OS allows it then you end up with
> the internal state of python messed up.
>
> To implement this I think requires the re code to implement the timeout.
>
> Better is for the OP to fix the re to not back track so much or to work on
> the
> input string in chunks.
>
If the regex is expensive enough to warrant it, you could use a subprocess
- they are killable.

From h.goebel at crazy-compilers.com  Mon Dec  7 05:54:59 2020
From: h.goebel at crazy-compilers.com (Hartmut Goebel)
Date: Mon, 7 Dec 2020 11:54:59 +0100
Subject: Best-practice for formatted string literals and localization?
In-Reply-To: <CAPTjJmrVRC6Y8JM7TAUWBxMgOzYVOgr1Lu9yDxWW8Uk6+Z4L=A@mail.gmail.com>
References: <677f5213-9d52-0289-4152-b2a9190f7fe1@crazy-compilers.com>
 <CAPTjJmrVRC6Y8JM7TAUWBxMgOzYVOgr1Lu9yDxWW8Uk6+Z4L=A@mail.gmail.com>
Message-ID: <81b62b47-6c46-65d1-4cb7-4c8df58c0f4c@crazy-compilers.com>

Am 30.11.20 um 19:58 schrieb Chris Angelico:
> Not really, no.

Thanks for confirming my apprehension.

-- 
Regards
Hartmut Goebel

| Hartmut Goebel          | h.goebel at crazy-compilers.com               |
| www.crazy-compilers.com | compilers which you thought are impossible |


From h.goebel at crazy-compilers.com  Mon Dec  7 05:56:43 2020
From: h.goebel at crazy-compilers.com (Hartmut Goebel)
Date: Mon, 7 Dec 2020 11:56:43 +0100
Subject: Best-practice for formatted string literals and localization?
In-Reply-To: <24518.36381.933046.754777@ixdm.fritz.box>
References: <677f5213-9d52-0289-4152-b2a9190f7fe1@crazy-compilers.com>
 <24518.36381.933046.754777@ixdm.fritz.box>
Message-ID: <af732d77-a46e-0815-7571-3a256d0886bc@crazy-compilers.com>

Am 01.12.20 um 19:40 schrieb Dieter Maurer:
> Usually, the translation machinery has special ways to
> provide parameters for translations.
> For example with `zope.i18nmessageid`, you can use
> `_(msg, mapping=<parameter_dict>)` to provide parameters
> to the translations -- as in your case `count`).
> Check, what parameter support your translation machinery support.

Thanks for this hint. I'm using the stdlib, which AFAIU does not support 
that. (Anyhow it would be easy to implement such a wrapper)

-- 
Regards
Hartmut Goebel

| Hartmut Goebel          | h.goebel at crazy-compilers.com               |
| www.crazy-compilers.com | compilers which you thought are impossible |


From tjol at tjol.eu  Mon Dec  7 09:46:47 2020
From: tjol at tjol.eu (Thomas Jollans)
Date: Mon, 7 Dec 2020 15:46:47 +0100
Subject: how to plot the FFT of a list of values
In-Reply-To: <rqh0dd$nv7$1@dont-email.me>
References: <86r1o4kwbo.fsf@example.com> <rqh0dd$nv7$1@dont-email.me>
Message-ID: <5a75fd39-c370-f875-2c36-5aa91c8744d8@tjol.eu>

On 05/12/2020 23:08, Christian Gollwitzer wrote:
> Am 05.12.20 um 18:16 schrieb Boris Dorestand:
>> I have 16 values of the period sequence 1, 2, 4, 8, 1, 2, 4, 8, ...? I
>> compute its fourier transform using
>>
>>>>> from scipy import fft, ifft
>>>>> x = [1,2,4,8,1,2,4,8]
>>>>> fft(x)
>> array([ 30. +0.j,?? 0. +0.j,? -6.+12.j,?? 0. +0.j, -10. +0.j, 0. +0.j,
>> ???????? -6.-12.j,?? 0. +0.j])
>>
>> Now how can I plot these values?? I would like to plot 16 values.? What
>> do I need to do here?? Can you show an example?
>
>
> Usually, for the FFT of real input data, you plot only the magnitude 
> or square of the complex array, and usually on a logscale. So:
>
> import pylab

Don't use pylab.

https://matplotlib.org/api/index.html#module-pylab

Use matplotlib.pyplot directly instead. "plt" is a popular shorthand:

from matplotlib import pyplot as plt

#...

plt.semilogy(...) # or plt.plot, etc.


- Thomas


> import numpy as np
>
> fx = fft(x)
>
> pylab.semilogy(np.abs(fx))
> pylab.show()
>
>
>
> ????Christian
>
>
>


From Bischoop at vimart.net  Mon Dec  7 10:48:27 2020
From: Bischoop at vimart.net (Bischoop)
Date: Mon, 7 Dec 2020 15:48:27 -0000 (UTC)
Subject: Letter replacer - suggestions?
Message-ID: <slrnrssjmb.3oh.Bischoop@vimart.net>


I worked on my wee script that replaces a letters: https://bpa.st/OYBQ .
I would like to have some suggestions about the code from more
experienced programmers, the code does work and do its job but perhaps
could work in a better way.

Thanks

From python at mrabarnett.plus.com  Mon Dec  7 12:12:02 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Mon, 7 Dec 2020 17:12:02 +0000
Subject: Letter replacer - suggestions?
In-Reply-To: <slrnrssjmb.3oh.Bischoop@vimart.net>
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
Message-ID: <0d1257d4-f665-dc14-0201-06eaa54c5ddf@mrabarnett.plus.com>

On 2020-12-07 15:48, Bischoop wrote:
> 
> I worked on my wee script that replaces a letters: https://bpa.st/OYBQ .
> I would like to have some suggestions about the code from more
> experienced programmers, the code does work and do its job but perhaps
> could work in a better way.
> 
> Thanks
> 

 > word = input( f'input word you want to change letters in: ')

There's no need for the f prefix.

 > print(f' Your word to change: ,{word}')

Is the comma a typo?

 > word_list = list(word)
 > change_this = input(f'Enter the letters you want to change: ')

There's no need for the f prefix.

 > replace_with = input(f'Enter the letters to replace with: ')

There's no need for the f prefix.

 > change_this_list = list(change_this)
 > replace_with_list = list(replace_with)
 >
 > while True:
 >     try:
 >         for element in word_list:
 >             for x in change_this_list:
 >                 if element == x:
 >                     to = word_list.index(element)
 >                     replace = change_this_list.index(x)
 >                     word_list[to] = replace_with_list[replace]
 >         new_word = ''.join(word_list)
 >         print(f'{new_word}')

The f-string is overkill. You might as well just have:

          print(new_word)

 >         break
 >     except:

Avoid a 'bare' except unless you _really_ mean it, which is virtually 
never. Catch only those exceptions that you're going to handle.

 >         print(f'nope')


You can make it a lot shorter and faster by using a dict. The entire 
while loop section can be replaced with:

replacements = dict(zip(change_this, replace_with))
new_word = ''.join(replacements.get(letter, letter) for letter in word)
print(new_word)

From torriem at gmail.com  Mon Dec  7 13:13:36 2020
From: torriem at gmail.com (Michael Torrie)
Date: Mon, 7 Dec 2020 11:13:36 -0700
Subject: Error
In-Reply-To: <581499158.4562022.1607364432970@mail.yahoo.com>
References: <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61.ref@yahoo.com>
 <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61@yahoo.com>
 <cd09cefe-2564-2f1e-1f0e-4615810a7d14@gmail.com>
 <581499158.4562022.1607364432970@mail.yahoo.com>
Message-ID: <10ab5569-2659-a268-f164-b08f7d8d2d2b@gmail.com>

On 12/7/20 11:07 AM, Barry Fitzgerald wrote:
> I did the pip install I did the pip install pygameThe pip install
> pgzero I get this error C:\Users\barol>pip install pgzeroDefaulting
> to user installation because normal site-packages is not
> writeableCollecting pgzero  Using cached pgzero-1.2-py3-none-any.whl
> (69 kB)Collecting numpy  Using cached
> numpy-1.19.4-cp39-cp39-win_amd64.whl (13.0 MB)Collecting
> pygame<2.0,>=1.9.2  Using cached pygame-1.9.6.tar.gz (3.2 MB)
> ERROR: Command errored out with exit status 1:     command:
> 'c:\program files\python39\python.exe' -c 'import sys, setuptools,
> tokenize; sys.argv[0] =
> '"'"'C:\\Users\\barol\\AppData\\Local\\Temp\\pip-install-loo9yev7\\pygame_5aee70f17f294e14b6187b13f07afa31\\setup.py'"'"';
> __file__='"'"'C:\\Users\\barol\\AppData\\Local\\Temp\\pip-install-loo9yev7\\pygame_5aee70f17f294e14b6187b13f07afa31\\setup.py'"'"';f=getattr(tokenize,
> '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"',
> '"'"'\n'"'"');f.close();exec(compile(code, __file__,
> '"'"'exec'"'"'))' egg_info --egg-base
> 'C:\Users\barol\AppData\Local\Temp\pip-pip-egg-info-rdmw_7gl'
> cwd:
> C:\Users\barol\AppData\Local\Temp\pip-install-loo9yev7\pygame_5aee70f17f294e14b6187b13f07afa31\
> Complete output (17 lines):
> 
> WARNING, No "Setup" File Exists, Running "buildconfig/config.py"
> Using WINDOWS configuration...
The problem is there is no pre-compiled PyGame Zero package yet for
Python 3.9.  So your system is trying to compile it from source.
Probably your best bet is to remove Python 3.9 and install Python 3.8.

From mats at wichmann.us  Mon Dec  7 13:29:21 2020
From: mats at wichmann.us (Mats Wichmann)
Date: Mon, 7 Dec 2020 11:29:21 -0700
Subject: Error
In-Reply-To: <10ab5569-2659-a268-f164-b08f7d8d2d2b@gmail.com>
References: <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61.ref@yahoo.com>
 <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61@yahoo.com>
 <cd09cefe-2564-2f1e-1f0e-4615810a7d14@gmail.com>
 <581499158.4562022.1607364432970@mail.yahoo.com>
 <10ab5569-2659-a268-f164-b08f7d8d2d2b@gmail.com>
Message-ID: <81d35ada-10f0-9ac9-f81b-65107fe11dbc@wichmann.us>

On 12/7/20 11:13 AM, Michael Torrie wrote:
> On 12/7/20 11:07 AM, Barry Fitzgerald wrote:
>> I did the pip install I did the pip install pygameThe pip install
>> pgzero I get this error C:\Users\barol>pip install pgzeroDefaulting
>> to user installation because normal site-packages is not
>> writeableCollecting pgzero  Using cached pgzero-1.2-py3-none-any.whl
>> (69 kB)Collecting numpy  Using cached
>> numpy-1.19.4-cp39-cp39-win_amd64.whl (13.0 MB)Collecting
>> pygame<2.0,>=1.9.2  Using cached pygame-1.9.6.tar.gz (3.2 MB)
>> ERROR: Command errored out with exit status 1:     command:
>> 'c:\program files\python39\python.exe' -c 'import sys, setuptools,
>> tokenize; sys.argv[0] =
>> '"'"'C:\\Users\\barol\\AppData\\Local\\Temp\\pip-install-loo9yev7\\pygame_5aee70f17f294e14b6187b13f07afa31\\setup.py'"'"';
>> __file__='"'"'C:\\Users\\barol\\AppData\\Local\\Temp\\pip-install-loo9yev7\\pygame_5aee70f17f294e14b6187b13f07afa31\\setup.py'"'"';f=getattr(tokenize,
>> '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"',
>> '"'"'\n'"'"');f.close();exec(compile(code, __file__,
>> '"'"'exec'"'"'))' egg_info --egg-base
>> 'C:\Users\barol\AppData\Local\Temp\pip-pip-egg-info-rdmw_7gl'
>> cwd:
>> C:\Users\barol\AppData\Local\Temp\pip-install-loo9yev7\pygame_5aee70f17f294e14b6187b13f07afa31\
>> Complete output (17 lines):
>>
>> WARNING, No "Setup" File Exists, Running "buildconfig/config.py"
>> Using WINDOWS configuration...
> The problem is there is no pre-compiled PyGame Zero package yet for
> Python 3.9.  So your system is trying to compile it from source.

... which nearly always fails on Windows, unless you're previously 
ensured your setup exactly matches what that project wants.

> Probably your best bet is to remove Python 3.9 and install Python 3.8.

You can check the status on pypi by searching for a package and then 
clicking on "Download files".  Doing that in this case shows that pygame 
2.0 is indeed available for Python 3.9:

https://pypi.org/project/pygame/#files

BUT, above it's trying to compile pygame 1.9.2, because *it* presumably 
doesn't have a Py3.9 version.  So the guess is that pgzero is pinned to 
a particular pygame version, and that version isn't available for 3.9, 
so this story may be a little more complex than most of them are. 
Unpacking it shows the requirement indeed excludes pygame 2.0:

pygame<2.0,>=1.9.2









From python at mrabarnett.plus.com  Mon Dec  7 13:30:39 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Mon, 7 Dec 2020 18:30:39 +0000
Subject: Error
In-Reply-To: <10ab5569-2659-a268-f164-b08f7d8d2d2b@gmail.com>
References: <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61.ref@yahoo.com>
 <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61@yahoo.com>
 <cd09cefe-2564-2f1e-1f0e-4615810a7d14@gmail.com>
 <581499158.4562022.1607364432970@mail.yahoo.com>
 <10ab5569-2659-a268-f164-b08f7d8d2d2b@gmail.com>
Message-ID: <34f710ec-68f1-5105-0b3f-701792a1109d@mrabarnett.plus.com>

On 2020-12-07 18:13, Michael Torrie wrote:
> On 12/7/20 11:07 AM, Barry Fitzgerald wrote:
>> I did the pip install I did the pip install pygameThe pip install
>> pgzero I get this error C:\Users\barol>pip install pgzeroDefaulting
>> to user installation because normal site-packages is not
>> writeableCollecting pgzero  Using cached pgzero-1.2-py3-none-any.whl
>> (69 kB)Collecting numpy  Using cached
>> numpy-1.19.4-cp39-cp39-win_amd64.whl (13.0 MB)Collecting
>> pygame<2.0,>=1.9.2  Using cached pygame-1.9.6.tar.gz (3.2 MB)
>> ERROR: Command errored out with exit status 1:     command:
>> 'c:\program files\python39\python.exe' -c 'import sys, setuptools,
>> tokenize; sys.argv[0] =
>> '"'"'C:\\Users\\barol\\AppData\\Local\\Temp\\pip-install-loo9yev7\\pygame_5aee70f17f294e14b6187b13f07afa31\\setup.py'"'"';
>> __file__='"'"'C:\\Users\\barol\\AppData\\Local\\Temp\\pip-install-loo9yev7\\pygame_5aee70f17f294e14b6187b13f07afa31\\setup.py'"'"';f=getattr(tokenize,
>> '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"',
>> '"'"'\n'"'"');f.close();exec(compile(code, __file__,
>> '"'"'exec'"'"'))' egg_info --egg-base
>> 'C:\Users\barol\AppData\Local\Temp\pip-pip-egg-info-rdmw_7gl'
>> cwd:
>> C:\Users\barol\AppData\Local\Temp\pip-install-loo9yev7\pygame_5aee70f17f294e14b6187b13f07afa31\
>> Complete output (17 lines):
>> 
>> WARNING, No "Setup" File Exists, Running "buildconfig/config.py"
>> Using WINDOWS configuration...
> The problem is there is no pre-compiled PyGame Zero package yet for
> Python 3.9.  So your system is trying to compile it from source.
> Probably your best bet is to remove Python 3.9 and install Python 3.8.
> 
There's no need to remove Python 3.9 first; Python 3.8 can be installed 
alongside it.

From python at mrabarnett.plus.com  Mon Dec  7 14:31:26 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Mon, 7 Dec 2020 19:31:26 +0000
Subject: Error
In-Reply-To: <81d35ada-10f0-9ac9-f81b-65107fe11dbc@wichmann.us>
References: <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61.ref@yahoo.com>
 <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61@yahoo.com>
 <cd09cefe-2564-2f1e-1f0e-4615810a7d14@gmail.com>
 <581499158.4562022.1607364432970@mail.yahoo.com>
 <10ab5569-2659-a268-f164-b08f7d8d2d2b@gmail.com>
 <81d35ada-10f0-9ac9-f81b-65107fe11dbc@wichmann.us>
Message-ID: <ad531726-da5a-9f12-2c04-f2ff157a2af1@mrabarnett.plus.com>

On 2020-12-07 18:29, Mats Wichmann wrote:
> On 12/7/20 11:13 AM, Michael Torrie wrote:
>> On 12/7/20 11:07 AM, Barry Fitzgerald wrote:
>>> I did the pip install I did the pip install pygameThe pip install
>>> pgzero I get this error C:\Users\barol>pip install pgzeroDefaulting
>>> to user installation because normal site-packages is not
>>> writeableCollecting pgzero  Using cached pgzero-1.2-py3-none-any.whl
>>> (69 kB)Collecting numpy  Using cached
>>> numpy-1.19.4-cp39-cp39-win_amd64.whl (13.0 MB)Collecting
>>> pygame<2.0,>=1.9.2  Using cached pygame-1.9.6.tar.gz (3.2 MB)
>>> ERROR: Command errored out with exit status 1:     command:
>>> 'c:\program files\python39\python.exe' -c 'import sys, setuptools,
>>> tokenize; sys.argv[0] =
>>> '"'"'C:\\Users\\barol\\AppData\\Local\\Temp\\pip-install-loo9yev7\\pygame_5aee70f17f294e14b6187b13f07afa31\\setup.py'"'"';
>>> __file__='"'"'C:\\Users\\barol\\AppData\\Local\\Temp\\pip-install-loo9yev7\\pygame_5aee70f17f294e14b6187b13f07afa31\\setup.py'"'"';f=getattr(tokenize,
>>> '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"',
>>> '"'"'\n'"'"');f.close();exec(compile(code, __file__,
>>> '"'"'exec'"'"'))' egg_info --egg-base
>>> 'C:\Users\barol\AppData\Local\Temp\pip-pip-egg-info-rdmw_7gl'
>>> cwd:
>>> C:\Users\barol\AppData\Local\Temp\pip-install-loo9yev7\pygame_5aee70f17f294e14b6187b13f07afa31\
>>> Complete output (17 lines):
>>>
>>> WARNING, No "Setup" File Exists, Running "buildconfig/config.py"
>>> Using WINDOWS configuration...
>> The problem is there is no pre-compiled PyGame Zero package yet for
>> Python 3.9.  So your system is trying to compile it from source.
> 
> ... which nearly always fails on Windows, unless you're previously
> ensured your setup exactly matches what that project wants.
> 
>> Probably your best bet is to remove Python 3.9 and install Python 3.8.
> 
> You can check the status on pypi by searching for a package and then
> clicking on "Download files".  Doing that in this case shows that pygame
> 2.0 is indeed available for Python 3.9:
> 
> https://pypi.org/project/pygame/#files
> 
> BUT, above it's trying to compile pygame 1.9.2, because *it* presumably
> doesn't have a Py3.9 version.  So the guess is that pgzero is pinned to
> a particular pygame version, and that version isn't available for 3.9,
> so this story may be a little more complex than most of them are.
> Unpacking it shows the requirement indeed excludes pygame 2.0:
> 
> pygame<2.0,>=1.9.2
> 
Christoph Gohlke's site has wheels for pygame on Python 3.9:

https://www.lfd.uci.edu/~gohlke/pythonlibs/#pygame

From tjreedy at udel.edu  Mon Dec  7 00:59:12 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 7 Dec 2020 00:59:12 -0500
Subject: Learning tkinter - a grid problem
In-Reply-To: <rqidhm$i72$1@ciao.gmane.io>
References: <rqgl5d$8ia$1@gioia.aioe.org>
 <c245040c-1c92-9f0a-6f35-74313e417c6a@web.de> <rqidhm$i72$1@ciao.gmane.io>
Message-ID: <rqkgbi$13si$1@ciao.gmane.io>

On 12/6/2020 5:59 AM, Terry Reedy wrote:
> On 12/6/2020 3:11 AM, Sibylle Koczian wrote:
>> Am 05.12.2020 um 19:56 schrieb Paulo da Silva:
> 
>>> Why this example does not work?
>>> ------------------
>>> from tkinter import *
>>>
>>> root=Tk()
>>> root.geometry("400x200")
>>> S=Scrollbar(root)
>>> T=Text(root)
>> ...
>>> mainloop()
> 
>> Shouldn't that be
>> root.mainloop()
>> ?
> 
> Yes.? The * import does not turn method into module functions.

But no, sort of.  MRAB is correct that there is (an undocumented) module 
function by the same name.  It calls tkinter._default_root.tk.mainloop 
if _default_root is not None.  This is true if 
tkinter._support_default_root == 1 (the default, but set to 0 in IDLE) 
and tkinter.Tk has been called at least once.

-- 
Terry Jan Reedy



From tsano at tiscali.it  Mon Dec  7 11:59:01 2020
From: tsano at tiscali.it (=?iso-8859-1?Q?Tito_San=F2?=)
Date: Mon, 7 Dec 2020 17:59:01 +0100
Subject: linear algebric equations
Message-ID: <000401d6ccba$43cab5f0$cb6021d0$@tiscali.it>

Regarding the solution of linear algebraic equations I noticed a big
difference in the computation

time in Python compared to the old fortran language.

I have compared both the linelg and lapack.dgesv-lapack.zgesv modules with
the fortan: dgelg and f04adf. 

The difference in computation time is enormous:

for example for 430 degrees of freedom it is about 24 min in Python versus
about 1 sec in fortran.

Is it possible to get better performance in Python?

Thanks in advance  

Tito Sano? 

Roma Italy

Cell: 339 6903895

 


From grant.b.edwards at gmail.com  Mon Dec  7 13:36:36 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Mon, 7 Dec 2020 18:36:36 -0000 (UTC)
Subject: Letter replacer - suggestions?
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
 <0d1257d4-f665-dc14-0201-06eaa54c5ddf@mrabarnett.plus.com>
Message-ID: <rqlsnk$jh9$2@ciao.gmane.io>

On 2020-12-07, MRAB <python at mrabarnett.plus.com> wrote:

> Avoid a 'bare' except unless you _really_ mean it, which is
> virtually never. Catch only those exceptions that you're going to
> handle.

And sometimes "handling" is just printing some extra stuff and then
re-raising the original exception:

    try:
        something():
    except:
        print(<whatever might be helpful for troubleshooting>)
        raise



From Joseph.Schachner at Teledyne.com  Mon Dec  7 14:48:51 2020
From: Joseph.Schachner at Teledyne.com (Schachner, Joseph)
Date: Mon, 7 Dec 2020 19:48:51 +0000
Subject: Letter replacer - suggestions?
In-Reply-To: <slrnrssjmb.3oh.Bischoop@vimart.net>
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
Message-ID: <BN8PR14MB28514716C9EEED509DA0EA1AF5CE0@BN8PR14MB2851.namprd14.prod.outlook.com>

The only comment I have is that you didn't check the inputs at all.  Suppose the word I type in is "1234".   1234 will turn into an int, not a string.
You can't index through an int, it's one thing.  So the program will probably throw an error.

If the word at least starts with a letter, then it will be a string.   If I say I want to replace "?" that may not exist in the string, but that's OK. 

---- Joseph S. 

-----Original Message-----
From: Bischoop <Bischoop at vimart.net> 
Sent: Monday, December 7, 2020 10:48 AM
To: python-list at python.org
Subject: Letter replacer - suggestions?


I worked on my wee script that replaces a letters: https://bpa.st/OYBQ .
I would like to have some suggestions about the code from more experienced programmers, the code does work and do its job but perhaps could work in a better way.

Thanks


From rosuav at gmail.com  Mon Dec  7 14:53:07 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 8 Dec 2020 06:53:07 +1100
Subject: Letter replacer - suggestions?
In-Reply-To: <rqlsnk$jh9$2@ciao.gmane.io>
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
 <0d1257d4-f665-dc14-0201-06eaa54c5ddf@mrabarnett.plus.com>
 <rqlsnk$jh9$2@ciao.gmane.io>
Message-ID: <CAPTjJmqxs=5VhSXv1tk=L5AmVimWBiidsjHhHgnKVuefNF-icg@mail.gmail.com>

On Tue, Dec 8, 2020 at 6:41 AM Grant Edwards <grant.b.edwards at gmail.com> wrote:
>
> On 2020-12-07, MRAB <python at mrabarnett.plus.com> wrote:
>
> > Avoid a 'bare' except unless you _really_ mean it, which is
> > virtually never. Catch only those exceptions that you're going to
> > handle.
>
> And sometimes "handling" is just printing some extra stuff and then
> re-raising the original exception:
>
>     try:
>         something():
>     except:
>         print(<whatever might be helpful for troubleshooting>)
>         raise
>

Even there, I'd most often use "except BaseException as e:", other
than in a very few situations. The only time I have recently used a
bare except is when making use of the traceback module:

try:
    ...
except:
    with open("notes.err", "a") as err:
        traceback.print_exc(file=err)
    raise

since print_exc() can go fetch the exception via sys.exc_info().

ChrisA

From rosuav at gmail.com  Mon Dec  7 14:54:45 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 8 Dec 2020 06:54:45 +1100
Subject: Letter replacer - suggestions?
In-Reply-To: <BN8PR14MB28514716C9EEED509DA0EA1AF5CE0@BN8PR14MB2851.namprd14.prod.outlook.com>
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
 <BN8PR14MB28514716C9EEED509DA0EA1AF5CE0@BN8PR14MB2851.namprd14.prod.outlook.com>
Message-ID: <CAPTjJmrpAphTTLA75yH7iGW6Cq8A52556=drLRt-yBDEjYYXFQ@mail.gmail.com>

On Tue, Dec 8, 2020 at 6:51 AM Schachner, Joseph
<Joseph.Schachner at teledyne.com> wrote:
>
> The only comment I have is that you didn't check the inputs at all.  Suppose the word I type in is "1234".   1234 will turn into an int, not a string.
> You can't index through an int, it's one thing.  So the program will probably throw an error.

Not sure what you mean here. The input() function always returns a
string, even if it's nothing but decimal digits.

(If you're using an ancient version of Python, then it will evaluate
the input, which would mean digits turn into an integer, but other
things will just error out - they won't be strings. Also, all the
f-strings in the OP's code wouldn't work, so that's irrelevant here.)

ChrisA

From inhahe at gmail.com  Mon Dec  7 14:58:45 2020
From: inhahe at gmail.com (inhahe)
Date: Mon, 7 Dec 2020 14:58:45 -0500
Subject: Letter replacer - suggestions?
In-Reply-To: <slrnrssjmb.3oh.Bischoop@vimart.net>
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
Message-ID: <CAPeSgWrZO847NTa--gnVAYpqRG=2eddAweFNxndAde8OaO25xw@mail.gmail.com>

Besides what others have said (especially re using a dict instead), I think
it's unpythonic/can result in unexpected behavior to change a list as it's
being iterated over. Your modified word_list should be a separate list, I
think.
Also, if you use enumerate(), you won't have to use .index and it would be
more efficient.
And I'm not sure what the 'while True' accomplishes. Seems it would put it
in an endless loop? If the 'while True' were in the beginning of the
program, before the inputs, it would make more sense. (And in that case
you'd probably want to break the loop if `word` is empty)

On Mon, Dec 7, 2020 at 10:51 AM Bischoop <Bischoop at vimart.net> wrote:

>
> I worked on my wee script that replaces a letters: https://bpa.st/OYBQ .
> I would like to have some suggestions about the code from more
> experienced programmers, the code does work and do its job but perhaps
> could work in a better way.
>
> Thanks
> --
> https://mail.python.org/mailman/listinfo/python-list
>

From jon+usenet at unequivocal.eu  Mon Dec  7 15:07:40 2020
From: jon+usenet at unequivocal.eu (Jon Ribbens)
Date: Mon, 7 Dec 2020 20:07:40 -0000 (UTC)
Subject: Letter replacer - suggestions?
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
 <0d1257d4-f665-dc14-0201-06eaa54c5ddf@mrabarnett.plus.com>
 <rqlsnk$jh9$2@ciao.gmane.io>
 <CAPTjJmqxs=5VhSXv1tk=L5AmVimWBiidsjHhHgnKVuefNF-icg@mail.gmail.com>
 <mailman.329.1607370801.7193.python-list@python.org>
Message-ID: <slrnrst2sc.55g.jon+usenet@raven.unequivocal.eu>

On 2020-12-07, Chris Angelico <rosuav at gmail.com> wrote:
> On Tue, Dec 8, 2020 at 6:41 AM Grant Edwards <grant.b.edwards at gmail.com> wrote:
>> On 2020-12-07, MRAB <python at mrabarnett.plus.com> wrote:
>> > Avoid a 'bare' except unless you _really_ mean it, which is
>> > virtually never. Catch only those exceptions that you're going to
>> > handle.
>>
>> And sometimes "handling" is just printing some extra stuff and then
>> re-raising the original exception:
>>
>>     try:
>>         something():
>>     except:
>>         print(<whatever might be helpful for troubleshooting>)
>>         raise
>>
>
> Even there, I'd most often use "except BaseException as e:", other
> than in a very few situations. The only time I have recently used a
> bare except is when making use of the traceback module:
>
> try:
>     ...
> except:
>     with open("notes.err", "a") as err:
>         traceback.print_exc(file=err)
>     raise
>
> since print_exc() can go fetch the exception via sys.exc_info().

... but even if you do think you want "except BaseException:" or
"except:", you almost never actually do - you almost certainly want
"except Exception:", because the former two will stop sys.exit()
from working, or the user from pressing ctrl-C.

From rosuav at gmail.com  Mon Dec  7 15:24:32 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 8 Dec 2020 07:24:32 +1100
Subject: Letter replacer - suggestions?
In-Reply-To: <slrnrst2sc.55g.jon+usenet@raven.unequivocal.eu>
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
 <0d1257d4-f665-dc14-0201-06eaa54c5ddf@mrabarnett.plus.com>
 <rqlsnk$jh9$2@ciao.gmane.io>
 <CAPTjJmqxs=5VhSXv1tk=L5AmVimWBiidsjHhHgnKVuefNF-icg@mail.gmail.com>
 <mailman.329.1607370801.7193.python-list@python.org>
 <slrnrst2sc.55g.jon+usenet@raven.unequivocal.eu>
Message-ID: <CAPTjJmq1A7YLD4Courvxyi_2Bk2C+Ht8jx6tOmR3QGdqXjpS5w@mail.gmail.com>

On Tue, Dec 8, 2020 at 7:11 AM Jon Ribbens via Python-list
<python-list at python.org> wrote:
>
> On 2020-12-07, Chris Angelico <rosuav at gmail.com> wrote:
> > On Tue, Dec 8, 2020 at 6:41 AM Grant Edwards <grant.b.edwards at gmail.com> wrote:
> >> On 2020-12-07, MRAB <python at mrabarnett.plus.com> wrote:
> >> > Avoid a 'bare' except unless you _really_ mean it, which is
> >> > virtually never. Catch only those exceptions that you're going to
> >> > handle.
> >>
> >> And sometimes "handling" is just printing some extra stuff and then
> >> re-raising the original exception:
> >>
> >>     try:
> >>         something():
> >>     except:
> >>         print(<whatever might be helpful for troubleshooting>)
> >>         raise
> >>
> >
> > Even there, I'd most often use "except BaseException as e:", other
> > than in a very few situations. The only time I have recently used a
> > bare except is when making use of the traceback module:
> >
> > try:
> >     ...
> > except:
> >     with open("notes.err", "a") as err:
> >         traceback.print_exc(file=err)
> >     raise
> >
> > since print_exc() can go fetch the exception via sys.exc_info().
>
> ... but even if you do think you want "except BaseException:" or
> "except:", you almost never actually do - you almost certainly want
> "except Exception:", because the former two will stop sys.exit()
> from working, or the user from pressing ctrl-C.

For "log and reraise" handlers, actually I usually *do* want to see
those. The goal of these is to report the exception in some different
way from the normal one, and maybe figuring out why some subsystem is
dying inexplicably; and a KeyboardInterrupt would definitely be of
note there.

ChrisA

From drsalists at gmail.com  Mon Dec  7 15:51:34 2020
From: drsalists at gmail.com (Dan Stromberg)
Date: Mon, 7 Dec 2020 12:51:34 -0800
Subject: linear algebric equations
In-Reply-To: <000401d6ccba$43cab5f0$cb6021d0$@tiscali.it>
References: <000401d6ccba$43cab5f0$cb6021d0$@tiscali.it>
Message-ID: <CAGGBd_rYSLq7ZRhnMJpTcpjBb=Mvv3LOS5t1NxJFdZRwmzphdg@mail.gmail.com>

On Mon, Dec 7, 2020 at 11:36 AM Tito San? <tsano at tiscali.it> wrote:

> Regarding the solution of linear algebraic equations I noticed a big
> difference in the computation
>
> time in Python compared to the old fortran language.
>
> I have compared both the linelg and lapack.dgesv-lapack.zgesv modules with
> the fortan: dgelg and f04adf.
>
> The difference in computation time is enormous:
>
> for example for 430 degrees of freedom it is about 24 min in Python versus
> about 1 sec in fortran.
>
> Is it possible to get better performance in Python?
>

Can you make your test code available for examination?

If you are using CPython, are you also using numpy? Or numba?

If you are using pure Python, have you tried Pypy3?

HTH.

From larry.martell at gmail.com  Mon Dec  7 17:06:39 2020
From: larry.martell at gmail.com (Larry Martell)
Date: Mon, 7 Dec 2020 17:06:39 -0500
Subject: list of dictionaries search using kwargs
Message-ID: <CACwCsY66qA9rFWNnpEoyx+gLSNEXgQnW0UQSD4MTLhky7bGCOw@mail.gmail.com>

I have a class that has an object that contains a list of dicts. I
want to have a class method that takes a variable number of key/value
pairs and searches the list and returns the item that matches the
arguments.

If I know the key value pairs I can do something like this:

instance = next(item for item in data] if\
           item["appCode"] == 1 and\
           item["componentCode"] == "DB" and\
           item["environmentEnumID"] == 12 and\
           item["serverName"] == 'foo', None)

But in my class method if I have:

    def find_data_row(self, **kwargs):

and I call it:

find_data_row(appCode=1, componentCode='DB', ...)

How can I do the search in a pythonic way?

From Marco.Sulla.Python at gmail.com  Mon Dec  7 17:16:36 2020
From: Marco.Sulla.Python at gmail.com (Marco Sulla)
Date: Mon, 7 Dec 2020 23:16:36 +0100
Subject: Letter replacer - suggestions?
In-Reply-To: <CAPTjJmq1A7YLD4Courvxyi_2Bk2C+Ht8jx6tOmR3QGdqXjpS5w@mail.gmail.com>
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
 <0d1257d4-f665-dc14-0201-06eaa54c5ddf@mrabarnett.plus.com>
 <rqlsnk$jh9$2@ciao.gmane.io>
 <CAPTjJmqxs=5VhSXv1tk=L5AmVimWBiidsjHhHgnKVuefNF-icg@mail.gmail.com>
 <mailman.329.1607370801.7193.python-list@python.org>
 <slrnrst2sc.55g.jon+usenet@raven.unequivocal.eu>
 <CAPTjJmq1A7YLD4Courvxyi_2Bk2C+Ht8jx6tOmR3QGdqXjpS5w@mail.gmail.com>
Message-ID: <CABbU2U9oGa-x3+VFxpweoSfpN5Dk7XP7L+PEWHS6+WFHBkReLA@mail.gmail.com>

Not sure why you want to do this (it's schoolwork)? Anyway, this is my version:

word = input('input word you want to change letters in: ')

chars = tuple(word)
change_this = input('Enter the letters you want to change: ')
replace_with = input('Enter the letters to replace with: ')

if len(change_this) != len(replace_with):
    raise RuntimeError(
        "Letters to replace must be equals in number to letters you want " +
        "to change"
    )

change_chars = tuple(change_this)
replace_chars = tuple(replace_with)

new_chars = []

for ch in chars:
    try:
        i = change_chars.index(ch)
    except ValueError:
        new_chars.append(ch)
    else:
        new_chars.append(replace_chars[i])

From Marco.Sulla.Python at gmail.com  Mon Dec  7 17:28:04 2020
From: Marco.Sulla.Python at gmail.com (Marco Sulla)
Date: Mon, 7 Dec 2020 23:28:04 +0100
Subject: list of dictionaries search using kwargs
In-Reply-To: <CACwCsY66qA9rFWNnpEoyx+gLSNEXgQnW0UQSD4MTLhky7bGCOw@mail.gmail.com>
References: <CACwCsY66qA9rFWNnpEoyx+gLSNEXgQnW0UQSD4MTLhky7bGCOw@mail.gmail.com>
Message-ID: <CABbU2U8=SonfiEhHCj-08ReSxw_3TncQH3jzGW3x2u2aPN4KFw@mail.gmail.com>

You can return dictionaries that returns True if

(a.items() & kwargs.items()) == kwargs.items()

when `a` is one of your dicts.

From larry.martell at gmail.com  Mon Dec  7 17:33:06 2020
From: larry.martell at gmail.com (Larry Martell)
Date: Mon, 7 Dec 2020 17:33:06 -0500
Subject: list of dictionaries search using kwargs
In-Reply-To: <CABbU2U8=SonfiEhHCj-08ReSxw_3TncQH3jzGW3x2u2aPN4KFw@mail.gmail.com>
References: <CACwCsY66qA9rFWNnpEoyx+gLSNEXgQnW0UQSD4MTLhky7bGCOw@mail.gmail.com>
 <CABbU2U8=SonfiEhHCj-08ReSxw_3TncQH3jzGW3x2u2aPN4KFw@mail.gmail.com>
Message-ID: <CACwCsY6tCNVPMExLiAx1z9z+isy-2QXDWbrODk11kei_aAB8MA@mail.gmail.com>

On Mon, Dec 7, 2020 at 5:29 PM Marco Sulla <Marco.Sulla.Python at gmail.com> wrote:
>
> You can return dictionaries that returns True if
>
> (a.items() & kwargs.items()) == kwargs.items()
>
> when `a` is one of your dicts.

But what is passed in kwargs will not necessarily have values for all
of the keys and I only want to check for matches with the ones passed
in.

From m at funkyhat.org  Mon Dec  7 17:42:30 2020
From: m at funkyhat.org (Matt Wheeler)
Date: Mon, 7 Dec 2020 22:42:30 +0000
Subject: list of dictionaries search using kwargs
In-Reply-To: <CACwCsY66qA9rFWNnpEoyx+gLSNEXgQnW0UQSD4MTLhky7bGCOw@mail.gmail.com>
References: <CACwCsY66qA9rFWNnpEoyx+gLSNEXgQnW0UQSD4MTLhky7bGCOw@mail.gmail.com>
Message-ID: <c5fb5265-fa79-4c8e-afef-79c266142e75@Spark>

for item in self.data:
?? ?if all(item[k] == v for k,v in kwargs.items()):
?? ? ? ?return item

Or

return [item for item in self.data if all(item[k] == v for k,v in kwargs.items())]

to return all matches

Beware though that either of these will be slow if your list of dicts is large.
If the list is large enough that this becomes slow, consider using a database (e.g. sqlite or other SQL DB) instead.
On 7 Dec 2020, 22:06 +0000, Larry Martell <larry.martell at gmail.com>, wrote:
> I have a class that has an object that contains a list of dicts. I
> want to have a class method that takes a variable number of key/value
> pairs and searches the list and returns the item that matches the
> arguments.
>
> If I know the key value pairs I can do something like this:
>
> instance = next(item for item in data] if\
> item["appCode"] == 1 and\
> item["componentCode"] == "DB" and\
> item["environmentEnumID"] == 12 and\
> item["serverName"] == 'foo', None)
>
> But in my class method if I have:
>
> def find_data_row(self, **kwargs):
>
> and I call it:
>
> find_data_row(appCode=1, componentCode='DB', ...)
>
> How can I do the search in a pythonic way?
> --
> https://mail.python.org/mailman/listinfo/python-list

From larry.martell at gmail.com  Mon Dec  7 17:53:37 2020
From: larry.martell at gmail.com (Larry Martell)
Date: Mon, 7 Dec 2020 17:53:37 -0500
Subject: list of dictionaries search using kwargs
In-Reply-To: <c5fb5265-fa79-4c8e-afef-79c266142e75@Spark>
References: <CACwCsY66qA9rFWNnpEoyx+gLSNEXgQnW0UQSD4MTLhky7bGCOw@mail.gmail.com>
 <c5fb5265-fa79-4c8e-afef-79c266142e75@Spark>
Message-ID: <CACwCsY6wpW2z807ZNgeDN4roeGHkFDc4L1N0KM5oUK57e4719A@mail.gmail.com>

On Mon, Dec 7, 2020 at 5:42 PM Matt Wheeler <m at funkyhat.org> wrote:
>
> for item in self.data:
>     if all(item[k] == v for k,v in kwargs.items()):
>         return item
>
> Or
>
> return [item for item in self.data if all(item[k] == v for k,v in kwargs.items())]
>
> to return all matches
>
> Beware though that either of these will be slow if your list of dicts is large.
> If the list is large enough that this becomes slow, consider using a database (e.g. sqlite or other SQL DB) instead.

Thanks! Works perfectly.

> On 7 Dec 2020, 22:06 +0000, Larry Martell <larry.martell at gmail.com>, wrote:
>
> I have a class that has an object that contains a list of dicts. I
>
> want to have a class method that takes a variable number of key/value
>
> pairs and searches the list and returns the item that matches the
>
> arguments.
>
>
> If I know the key value pairs I can do something like this:
>
>
> instance = next(item for item in data] if\
>
> item["appCode"] == 1 and\
>
> item["componentCode"] == "DB" and\
>
> item["environmentEnumID"] == 12 and\
>
> item["serverName"] == 'foo', None)
>
>
> But in my class method if I have:
>
>
> def find_data_row(self, **kwargs):
>
>
> and I call it:
>
>
> find_data_row(appCode=1, componentCode='DB', ...)
>
>
> How can I do the search in a pythonic way?
>
> --
>
> https://mail.python.org/mailman/listinfo/python-list

From torriem at gmail.com  Mon Dec  7 18:00:40 2020
From: torriem at gmail.com (Michael Torrie)
Date: Mon, 7 Dec 2020 16:00:40 -0700
Subject: Error
In-Reply-To: <34f710ec-68f1-5105-0b3f-701792a1109d@mrabarnett.plus.com>
References: <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61.ref@yahoo.com>
 <CBCB313E-5ABD-4C9F-BA5E-A5BCAC4E3D61@yahoo.com>
 <cd09cefe-2564-2f1e-1f0e-4615810a7d14@gmail.com>
 <581499158.4562022.1607364432970@mail.yahoo.com>
 <10ab5569-2659-a268-f164-b08f7d8d2d2b@gmail.com>
 <34f710ec-68f1-5105-0b3f-701792a1109d@mrabarnett.plus.com>
Message-ID: <7a51b88e-7d68-3c88-5344-f3eed6c6808f@gmail.com>

On 12/7/20 11:30 AM, MRAB wrote:
> There's no need to remove Python 3.9 first; Python 3.8 can be installed 
> alongside it.

Since the original poster is invoking python.exe directly, probably as
per the instructions in the book he's following, I fear having two
versions of python installed will just lead to confusion.  In his case,
I think it's best to just have Python 3.8 installed.  Although
pgzrun.exe will almost certainly execute the correct version of Python,
so probably wouldn't matter either way.


From python at mrabarnett.plus.com  Mon Dec  7 18:06:47 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Mon, 7 Dec 2020 23:06:47 +0000
Subject: list of dictionaries search using kwargs
In-Reply-To: <CACwCsY66qA9rFWNnpEoyx+gLSNEXgQnW0UQSD4MTLhky7bGCOw@mail.gmail.com>
References: <CACwCsY66qA9rFWNnpEoyx+gLSNEXgQnW0UQSD4MTLhky7bGCOw@mail.gmail.com>
Message-ID: <34eddbe0-67b4-48c3-d043-1347e3955700@mrabarnett.plus.com>

On 2020-12-07 22:06, Larry Martell wrote:
> I have a class that has an object that contains a list of dicts. I
> want to have a class method that takes a variable number of key/value
> pairs and searches the list and returns the item that matches the
> arguments.
> 
> If I know the key value pairs I can do something like this:
> 
> instance = next(item for item in data] if\
>             item["appCode"] == 1 and\
>             item["componentCode"] == "DB" and\
>             item["environmentEnumID"] == 12 and\
>             item["serverName"] == 'foo', None)
> 
> But in my class method if I have:
> 
>      def find_data_row(self, **kwargs):
> 
> and I call it:
> 
> find_data_row(appCode=1, componentCode='DB', ...)
> 
> How can I do the search in a pythonic way?
> 
An item is a match if:

     all(item[key] == value for key, value in kwargs.items())

or possibly:

     MISSING = object()

     all(item.get(key, MISSING) == value for key, value in kwargs.items())

Just iterate over the list of dicts until you find a match.

From PythonList at DancesWithMice.info  Mon Dec  7 18:08:28 2020
From: PythonList at DancesWithMice.info (dn)
Date: Tue, 8 Dec 2020 12:08:28 +1300
Subject: Letter replacer - suggestions?
In-Reply-To: <CABbU2U9oGa-x3+VFxpweoSfpN5Dk7XP7L+PEWHS6+WFHBkReLA@mail.gmail.com>
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
 <0d1257d4-f665-dc14-0201-06eaa54c5ddf@mrabarnett.plus.com>
 <rqlsnk$jh9$2@ciao.gmane.io>
 <CAPTjJmqxs=5VhSXv1tk=L5AmVimWBiidsjHhHgnKVuefNF-icg@mail.gmail.com>
 <mailman.329.1607370801.7193.python-list@python.org>
 <slrnrst2sc.55g.jon+usenet@raven.unequivocal.eu>
 <CAPTjJmq1A7YLD4Courvxyi_2Bk2C+Ht8jx6tOmR3QGdqXjpS5w@mail.gmail.com>
 <CABbU2U9oGa-x3+VFxpweoSfpN5Dk7XP7L+PEWHS6+WFHBkReLA@mail.gmail.com>
Message-ID: <800c3598-4d75-5681-65f1-04f3b5814201@DancesWithMice.info>

> word = input('input word you want to change letters in: ')
> 
> chars = tuple(word)
> change_this = input('Enter the letters you want to change: ')
> replace_with = input('Enter the letters to replace with: ')
> 
> if len(change_this) != len(replace_with):
>      raise RuntimeError(
>          "Letters to replace must be equals in number to letters you want " +
>          "to change"
>      )
> 
> change_chars = tuple(change_this)
> replace_chars = tuple(replace_with)
> 
> new_chars = []
> 
> for ch in chars:
>      try:
>          i = change_chars.index(ch)
>      except ValueError:
>          new_chars.append(ch)
>      else:
>          new_chars.append(replace_chars[i])


There are two 'phases' to this program:

1 collecting the input-data, and
2 performing a translation.

The second and third inputs must be the same length - hence the first 
if-condition (above).


Phase 1:

More user-friendly (considerate) ways to do this include:

- (if short strings) input the character-pairs as a unit:-

     while ... # decide upon a sentinel/loop-terminator
         in = input( "A character and its replacement" )
         source_character, replacement_character = in.split( ... )
         # insert appropriate criteria as ...
         source_list.append( source_character )
         replacement_list.append( replacement_character )

- (existing practice) alter the input() "prompt-strings" to be the same 
length, and thus assist the user to *see* that his/her two inputs [must] 
also 'match' in length! eg

Source  characters? abcdef?
Encoded characters? zyxwuv?


Phase 2:

The translation phase is most easily achieved with the built-in 
str.translate() - and likely faster! First the translation-table must be 
built, then the source-text(s) translated:

     source_str = "".join( source_list )
     replacement_str = "".join( replacement_list )
     # have to join (above) lists into strings for next line
     translation_table = str.maketrans( source_str, replacement_str )
     translation = word.translate( translation_table )

NB because maketrans() is a static method (of the str[ing] class) we 
must use the "str.".

NBB because str.maketrans() checks the length of the two 
translation-strings, wrapping that with try...except might be considered 
more 'pythonic' than the "first if-condition" (although "explicit is 
better...", Zen of Python)


For extra credit/re-factoring further:
(after learning the above 'straight-line' approaches and code constructs)

str.maketrans() will accept a single dict[ionary]. Accordingly, instead 
of collecting the translation data as two lists - which must then be 
converted into strings; (no matter which approach to 'phase 1' is 
preferred); consider building a translation-dictionary wherein each 
entry has the 'letter to be changed' as its "key", and its "data" is 
'the letter to replace [it] with'. Refactoring from the above:

     source_character, replacement_character = in.split( ... )
     translation_dict[ source_character ] = replacement_character
     translation_table = str.maketrans( translation_dict )
     translation = word.translate( translation_table )


Trust this adds to your 'adventures' in learning Python!


Web.Refs:
https://docs.python.org/3/library/stdtypes.html#text-sequence-type-str
https://www.askpython.com/python/string/python-string-translate
-- 
Regards =dn

From Marco.Sulla.Python at gmail.com  Mon Dec  7 18:15:57 2020
From: Marco.Sulla.Python at gmail.com (Marco Sulla)
Date: Tue, 8 Dec 2020 00:15:57 +0100
Subject: Letter replacer - suggestions?
In-Reply-To: <800c3598-4d75-5681-65f1-04f3b5814201@DancesWithMice.info>
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
 <0d1257d4-f665-dc14-0201-06eaa54c5ddf@mrabarnett.plus.com>
 <rqlsnk$jh9$2@ciao.gmane.io>
 <CAPTjJmqxs=5VhSXv1tk=L5AmVimWBiidsjHhHgnKVuefNF-icg@mail.gmail.com>
 <mailman.329.1607370801.7193.python-list@python.org>
 <slrnrst2sc.55g.jon+usenet@raven.unequivocal.eu>
 <CAPTjJmq1A7YLD4Courvxyi_2Bk2C+Ht8jx6tOmR3QGdqXjpS5w@mail.gmail.com>
 <CABbU2U9oGa-x3+VFxpweoSfpN5Dk7XP7L+PEWHS6+WFHBkReLA@mail.gmail.com>
 <800c3598-4d75-5681-65f1-04f3b5814201@DancesWithMice.info>
Message-ID: <CABbU2U93crSQHU8xqc3A6mChKxq0CMgzHkCQyHS9+aXHc89Yag@mail.gmail.com>

On Tue, 8 Dec 2020 at 00:10, dn via Python-list <python-list at python.org> wrote:
> The translation phase is most easily achieved with the built-in
> str.translate()

I forgot it :-)

From Marco.Sulla.Python at gmail.com  Mon Dec  7 18:19:15 2020
From: Marco.Sulla.Python at gmail.com (Marco Sulla)
Date: Tue, 8 Dec 2020 00:19:15 +0100
Subject: list of dictionaries search using kwargs
In-Reply-To: <CACwCsY6tCNVPMExLiAx1z9z+isy-2QXDWbrODk11kei_aAB8MA@mail.gmail.com>
References: <CACwCsY66qA9rFWNnpEoyx+gLSNEXgQnW0UQSD4MTLhky7bGCOw@mail.gmail.com>
 <CABbU2U8=SonfiEhHCj-08ReSxw_3TncQH3jzGW3x2u2aPN4KFw@mail.gmail.com>
 <CACwCsY6tCNVPMExLiAx1z9z+isy-2QXDWbrODk11kei_aAB8MA@mail.gmail.com>
Message-ID: <CABbU2U-g9vNGi6jar=ret8xLCkTosQHOkKtDJ+ooVun68WmHnw@mail.gmail.com>

On Mon, 7 Dec 2020 at 23:35, Larry Martell <larry.martell at gmail.com> wrote:
>
> On Mon, Dec 7, 2020 at 5:29 PM Marco Sulla <Marco.Sulla.Python at gmail.com> wrote:
> >
> > You can return dictionaries that returns True if
> >
> > (a.items() & kwargs.items()) == kwargs.items()
> >
> > when `a` is one of your dicts.
>
> But what is passed in kwargs will not necessarily have values for all
> of the keys

That's why I used the operator `&`. Anyway you already made your choice :-)

From PythonList at DancesWithMice.info  Mon Dec  7 20:02:45 2020
From: PythonList at DancesWithMice.info (dn)
Date: Tue, 8 Dec 2020 14:02:45 +1300
Subject: Letter replacer - suggestions?
In-Reply-To: <CABbU2U93crSQHU8xqc3A6mChKxq0CMgzHkCQyHS9+aXHc89Yag@mail.gmail.com>
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
 <0d1257d4-f665-dc14-0201-06eaa54c5ddf@mrabarnett.plus.com>
 <rqlsnk$jh9$2@ciao.gmane.io>
 <CAPTjJmqxs=5VhSXv1tk=L5AmVimWBiidsjHhHgnKVuefNF-icg@mail.gmail.com>
 <mailman.329.1607370801.7193.python-list@python.org>
 <slrnrst2sc.55g.jon+usenet@raven.unequivocal.eu>
 <CAPTjJmq1A7YLD4Courvxyi_2Bk2C+Ht8jx6tOmR3QGdqXjpS5w@mail.gmail.com>
 <CABbU2U9oGa-x3+VFxpweoSfpN5Dk7XP7L+PEWHS6+WFHBkReLA@mail.gmail.com>
 <800c3598-4d75-5681-65f1-04f3b5814201@DancesWithMice.info>
 <CABbU2U93crSQHU8xqc3A6mChKxq0CMgzHkCQyHS9+aXHc89Yag@mail.gmail.com>
Message-ID: <21898357-3436-b513-0408-51cd19e11614@DancesWithMice.info>

On 08/12/2020 12:15, Marco Sulla wrote:
> On Tue, 8 Dec 2020 at 00:10, dn via Python-list <python-list at python.org> wrote:
>> The translation phase is most easily achieved with the built-in
>> str.translate()
> 
> I forgot it :-)


That's down to the rich-ness of the Python eco-system!

IIRC (from previous posts) the OP is teaching him-/her-self Python. 
Thus, learning one-step at a time, building complexity in-line with 
confidence, is the way (s)he's going. Accordingly, each answer, building 
on the previous shows the way forward (as well as, the process of 
re-factoring)!

BTW his/her learn-by-doing approach is also the reason why I didn't 
write a complete-code answer.


Interestingly (at least, to me), the earlier response was me taking a 
break from writing a short paper (nothing-much to do with Python). 
Herewith some overlap of ideas:-

The aphorism claiming "two heads are better than one" is also the basis 
for what business-groups commonly call "brain-storming" (or 
"spit-balling", if you're 'in' marketing). However, did you know that 
"brain-storming" (in-person) seldom reaches the aspiration of finding 
'the best possible answer'?

Further, that if team-members work remotely, (first) 'attacking' a 
problem individually, and only after that, pooling their ideas to 
produce a plan; the chosen 'answer' will (likely) be much better!

Reasons: stated opinion of the "highest paid [wo]man in the room", 
dominant personalities, extrovert behavior, introvert behavior, I'd 
rather be sailing, ...

Thus: "Planning Poker" as a 'bottom-up', Agile, method for story/task 
(length) estimation!
-- 
Regards =dn

From pablogsal at gmail.com  Mon Dec  7 20:33:11 2020
From: pablogsal at gmail.com (Pablo Galindo Salgado)
Date: Tue, 8 Dec 2020 01:33:11 +0000
Subject: [RELEASE] Python 3.9.1 is now available,
 together with 3.10.0a3 and 3.8.7rc1
Message-ID: <CAFjbc8Fjd8ocOFvOGbBnfRMhhzh3=f_QUENge4Z3X-6jJTgmYg@mail.gmail.com>

It's starting to get very cold (at least on the Northern hemisphere) so we
have been carefully packaging a total of three new Python releases to keep
you warm these days!

Python 3.9.1 is the first maintenance release of Python 3.9, and also the
first version of Python to support macOS 11 Big Sur natively on Apple
Silicon. Go get it here:

https://www.python.org/downloads/release/python-391/

Maintenance releases for the 3.9 series will continue at regular bi-monthly
intervals, with **3.9.2** planned for Monday, 2021-02-08.

Python 3.10a3 is the third alpha release of Python 3.10. You can get it
here:

https://www.python.org/downloads/release/python-3100a3/

Python 3.10a3 is the release preview of the next maintenance release of
Python 3.8. You can get it here:

https://www.python.org/downloads/release/python-387rc1/

Assuming no critical problems are found prior to **2020-12-21** , the
currently scheduled release date for **3.8.7** , no code changes are
planned between this release candidate and the final release. That being
said, please keep in mind that this is a pre-release of 3.8.7 and as such
its main purpose is testing.

Your friendly release team,
Ned Deily, Steve Dower, Pablo Galindo, ?ukasz Langa

From tjol at tjol.eu  Mon Dec  7 11:22:16 2020
From: tjol at tjol.eu (Thomas Jollans)
Date: Mon, 7 Dec 2020 17:22:16 +0100
Subject: Letter replacer - suggestions?
In-Reply-To: <slrnrssjmb.3oh.Bischoop@vimart.net>
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
Message-ID: <9a9093ba-ca6c-6236-64d1-8db2b6df4a8e@tjol.eu>

On 07/12/2020 16:48, Bischoop wrote:
> I worked on my wee script that replaces a letters: https://bpa.st/OYBQ .
> I would like to have some suggestions about the code from more
> experienced programmers, the code does work and do its job but perhaps
> could work in a better way.
>
> Thanks


Sure!

First of all, the code could be simplified by using the replace() method 
of the str class 
(https://docs.python.org/3/library/stdtypes.html#str.replace).

Now a few comments on the code specifically:

 ??? while True:

What is this for? It looks like all it does is cause the program to get 
caught in an infinite loop if there's an exception...

 ??????? for element in word_list:
 ??????????? for x in change_this_list:

You can loop over strings as well - there's no need to convert them to 
lists.

 ??????? to = word_list.index(element)

There's a nice trick to get the index while looping: write

 ??????? for (idx, character) in enumerate(word):

then you don't have to use the index method. This also works if a 
character appears multiple times in the word, in which case I think your 
code will fail (but I haven't tried it)

(Obviously apply this to the other loop as well, mutadis mutandis, to 
get rid of both index() calls)

 ??????? word_list[to] = replace_with_list[replace]

Okay, this is something you can't do with a str because they're 
immutable. Generally I'd avoid modifying the thing you're looping over; 
it works in this case when you're replacing elements of a list, but it 
probably won't do what you want if you're deleting or adding items.

I'd put

new_word_list = []

somewhere at the top, and build it up element by element with 
new_word_list.append(). But what you're doing is fine too as long as you 
keep in mind that changing the thing you're looping over can be 
dangerous in other cases.


Hope this helps


Thomas



From tjreedy at udel.edu  Tue Dec  8 09:09:53 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 8 Dec 2020 09:09:53 -0500
Subject: [RELEASE] Python 3.9.1 is now available, together with 3.10.0a3
 and 3.8.7rc1
In-Reply-To: <CAFjbc8Fjd8ocOFvOGbBnfRMhhzh3=f_QUENge4Z3X-6jJTgmYg@mail.gmail.com>
References: <CAFjbc8Fjd8ocOFvOGbBnfRMhhzh3=f_QUENge4Z3X-6jJTgmYg@mail.gmail.com>
Message-ID: <rqo1fj$1379$1@ciao.gmane.io>

On 12/7/2020 8:33 PM, Pablo Galindo Salgado wrote:
> It's starting to get very cold (at least on the Northern hemisphere) so we
> have been carefully packaging a total of three new Python releases to keep
> you warm these days!
> 
> Python 3.9.1 is the first maintenance release of Python 3.9, and also the
> first version of Python to support macOS 11 Big Sur natively on Apple
> Silicon. Go get it here:
> 
> https://www.python.org/downloads/release/python-391/

On my Windows 10 machine, only test_locale failed.
https://bugs.python.org/issue37945
has not come to a conclusion yet.

> Maintenance releases for the 3.9 series will continue at regular bi-monthly
> intervals, with **3.9.2** planned for Monday, 2021-02-08.
> 
> Python 3.10a3 is the third alpha release of Python 3.10. You can get it
> here:
> 
> https://www.python.org/downloads/release/python-3100a3/

test_os test_pydoc test_webbrowser also fail for me

> Python 3.10a3 is the release preview of the next maintenance release of

This should be 3.8.7rc1 ...

> Python 3.8. You can get it here:
> 
> https://www.python.org/downloads/release/python-387rc1/

test_compileall also fails for me

> Assuming no critical problems are found prior to **2020-12-21** , the
> currently scheduled release date for **3.8.7** , no code changes are
> planned between this release candidate and the final release. That being
> said, please keep in mind that this is a pre-release of 3.8.7 and as such
> its main purpose is testing
-- 
Terry Jan Reedy


From fabiofz at gmail.com  Tue Dec  8 13:57:15 2020
From: fabiofz at gmail.com (Fabio Zadrozny)
Date: Tue, 8 Dec 2020 15:57:15 -0300
Subject: PyDev 8.1.0 Released
Message-ID: <CANXBEFrwhJ2rH2szdWUMTiu1UGxWsVd9b6ROPu-BxmX7ya3h2w@mail.gmail.com>

 PyDev 8.1.0 Release Highlights

   -

   *Interactive Console*
   - The selection for which console to open may be saved. (*#PyDev-1112*)
      - When the *current editor* option is selected, the related
      interpreter is no longer asked. (*#PyDev-1112*)
   -

   *Debugger* (updated to pydevd 2.2.0)
   - Better support for Python flags when auto-attaching to subprocesses.
      - Fixes to path translation (when debugging in a different machine).
      - Catch warnings related to *imp* import from *pkg_resources*.
      - No longer crashing when running with *Pyjion* (patch by Anthony
      Shaw).
   -

   *Others*
   - Code analysis now supports *from __future__ import anotations*. (
      *#PyDev-1040*)
      - AST pretty-printing supports printing slices. (*#PyDev-1106*)
      - Code-completion with auto imports for the builtin module is no
      longer shown. (*#PyDev-1117*)
      - MyPy messages from a different file are no longer shown in the
      current editor. (*#PyDev-1114*)

About PyDev

PyDev is an open-source Python IDE on top of Eclipse for Python, Jython and
IronPython development, now also available for Python on Visual Studio Code.

It comes with goodies such as code completion, syntax highlighting, syntax
analysis, code analysis, refactor, debug, interactive console, etc.

It is also available as a standalone through LiClipse with goodies such as
multiple cursors, theming and support for many other languages, such as
Django Templates, Jinja2, Html, JavaScript, etc.

Links:

PyDev: http://pydev.org
PyDev Blog: http://pydev.blogspot.com
PyDev on VSCode: http://pydev.org/vscode
LiClipse: http://www.liclipse.com
PyVmMonitor - Python Profiler: http://www.pyvmmonitor.com/

Cheers,

Fabio Zadrozny

From Joseph.Schachner at Teledyne.com  Tue Dec  8 14:07:57 2020
From: Joseph.Schachner at Teledyne.com (Schachner, Joseph)
Date: Tue, 8 Dec 2020 19:07:57 +0000
Subject: linear algebric equations
In-Reply-To: <000401d6ccba$43cab5f0$cb6021d0$@tiscali.it>
References: <000401d6ccba$43cab5f0$cb6021d0$@tiscali.it>
Message-ID: <BN8PR14MB28517F8E01AAE1BC55E73CF1F5CD0@BN8PR14MB2851.namprd14.prod.outlook.com>

Yes.  Import os, and use  os.system( ) to call your Fortran (or C) executable.  If the executable saves results in a file or files, Python can read them in an format a nice overall report.  In html or xml, if you like.

Using Python as glue,  the execution time will be exactly what it was for your executable, because Python will call it; and in a second of so after it finishes Python can read in results and format whatever report you like.

--- Joseph S.

-----Original Message-----
From: Tito San? <tsano at tiscali.it> 
Sent: Monday, December 7, 2020 11:59 AM
To: python-list at python.org
Subject: linear algebric equations

Regarding the solution of linear algebraic equations I noticed a big difference in the computation

time in Python compared to the old fortran language.

I have compared both the linelg and lapack.dgesv-lapack.zgesv modules with the fortan: dgelg and f04adf. 

The difference in computation time is enormous:

for example for 430 degrees of freedom it is about 24 min in Python versus about 1 sec in fortran.

Is it possible to get better performance in Python?

Thanks in advance  

Tito Sano' 

Roma Italy

Cell: 339 6903895

 



From Marco.Sulla.Python at gmail.com  Tue Dec  8 15:06:39 2020
From: Marco.Sulla.Python at gmail.com (Marco Sulla)
Date: Tue, 8 Dec 2020 21:06:39 +0100
Subject: linear algebric equations
In-Reply-To: <000401d6ccba$43cab5f0$cb6021d0$@tiscali.it>
References: <000401d6ccba$43cab5f0$cb6021d0$@tiscali.it>
Message-ID: <CABbU2U-LyGpiab02SVDp2aw--3OHnm8w4ERHr=uLSR6qd9zsgg@mail.gmail.com>

On Mon, 7 Dec 2020 at 20:38, Tito San? <tsano at tiscali.it> wrote:
> Is it possible to get better performance in Python?

Have you installed BLAS for Scipy? What OS do you have?

From auriocus at gmx.de  Tue Dec  8 15:05:54 2020
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Tue, 8 Dec 2020 21:05:54 +0100
Subject: linear algebric equations
In-Reply-To: <mailman.326.1607369772.7193.python-list@python.org>
References: <000401d6ccba$43cab5f0$cb6021d0$@tiscali.it>
 <mailman.326.1607369772.7193.python-list@python.org>
Message-ID: <f2e20965-155b-fb1f-a1c9-5b58afdf343a@gmx.de>

Am 07.12.20 um 17:59 schrieb Tito San?:
> Regarding the solution of linear algebraic equations I noticed a big
> difference in the computation
> 
> time in Python compared to the old fortran language.
> 
> I have compared both the linelg and lapack.dgesv-lapack.zgesv modules with
> the fortan: dgelg and f04adf.
> 
> The difference in computation time is enormous:
> 
> for example for 430 degrees of freedom it is about 24 min in Python versus
> about 1 sec in fortran.

There must be something seriously wrong. If I understand correctly, you 
want to solve an 430x430 matrix with LU decompositino (that is what 
dgesv from LAPACK does). The following code takes less than a second on 
my machine:

==============430.py==============
import numpy as np

# create a 430x430 random matrix
A = np.random.randn(430,430)

# right hand side
b = np.ones(430)

# solve it

x = np.linalg.solve(A, b)

print(x)
====================================


time python3 430.py
real	0m0.318s
user	0m0.292s
sys	0m0.046s

If it takes longer than 1s, there is something wrong with your system.

	Christian

From pbryan at anode.ca  Tue Dec  8 19:17:24 2020
From: pbryan at anode.ca (Paul Bryan)
Date: Tue, 08 Dec 2020 16:17:24 -0800
Subject: Property type hints?
Message-ID: <c6ca926e6a53320e1c0f55bc082fa9644c9e93ab.camel@anode.ca>

Would this be a reasonably correct way to annotate a property with a
type hint?

>>> class Foo:
...     bar: int
...     @property
...     def bar(self):
...         return 1
... 
>>> foo = Foo()
>>> import typing
>>> typing.get_type_hints(foo)
{'bar': <class 'int'>}

I could also decorate the property method return value:
...     def bar(self) -> int:

I don't see the point though, because you can't access it with get_type_hints.

From p_d_a_s_i_l_v_a_ns at nonetnoaddress.pt  Wed Dec  9 00:55:29 2020
From: p_d_a_s_i_l_v_a_ns at nonetnoaddress.pt (Paulo da Silva)
Date: Wed, 9 Dec 2020 05:55:29 +0000
Subject: numpy/python (image) problem
Message-ID: <rqposh$5i6$1@gioia.aioe.org>

Hi!

I am looking at some code, that I found somewhere in the internet, to
compute DCT for each 8x8 block in an gray (2D) image (512x512).

This is the code:

def dct2(a):
    return
scipy.fft.dct(scipy.fft.dct(a,axis=0,norm='ortho'),axis=1,norm='ortho')

imsize=im.shape
dct=np.zeros(imsize)

# Do 8x8 DCT on image (in-place)
for i in r_[:imsize[0]:8]: # Seems the same as "for i in
np.arange(0,imsize[0],8)"!
    for j in r_[:imsize[1]:8]:
        dct[i:(i+8),j:(j+8)]=dct2(im[i:(i+8),j:(j+8)])

I tried to do the same thing with:

imsize=im.shape
im8=im.reshape(imsize[0]*imsize[1]//8//8,8,8)
dct_test=np.asarray([dct2(im8x) for im8x in im8])
dct_test=dct_test.reshape(imsize)

so that dct_test should be equal to (previous) dct.
But they are completely different.

What am I doing wrong?

Thanks a lot.

From avianshgaur at gmail.com  Wed Dec  9 11:08:46 2020
From: avianshgaur at gmail.com (avinash gaur)
Date: Wed, 9 Dec 2020 21:38:46 +0530
Subject: Python idle did not open even after trying many times
Message-ID: <CAP03=D4nsT+fkYOSuDaDiRoT50L1cEVZgj4e=4G-CtrB95u7gw@mail.gmail.com>

Dear Sir/Mam,
I am facing a problem with Python Idle. I am unable to open python idle
even after clicking on it so many times. I am using Python 3.7 on Windows.
I have already installed and uninstalled python 3.7 so many times. But it
is not working
Any help will be appreciated
Thanking you

From siddarthadiga at gmail.com  Wed Dec  9 00:34:03 2020
From: siddarthadiga at gmail.com (Siddarth Adiga)
Date: Wed, 9 Dec 2020 11:04:03 +0530
Subject: Unable to download
Message-ID: <CA+X5SuwFatkzD9ePCQn9ccECgK_WCKyAxkZswY+vk33hMKoJuw@mail.gmail.com>

Hello. I wanted to download the Python Version 3.9.1 but it said there was
already another version of Python already installed. But I have deleted the
program from the ADD OR REMOVE PROGRAMS option. But still I am unable to
download it. Please help...

From p_d_a_s_i_l_v_a_ns at nonetnoaddress.pt  Wed Dec  9 13:21:13 2020
From: p_d_a_s_i_l_v_a_ns at nonetnoaddress.pt (Paulo da Silva)
Date: Wed, 9 Dec 2020 18:21:13 +0000
Subject: numpy/python (image) problem
References: <rqposh$5i6$1@gioia.aioe.org>
Message-ID: <rqr4io$1bkm$1@gioia.aioe.org>

?s 05:55 de 09/12/20, Paulo da Silva escreveu:
> Hi!
> 
> I am looking at some code, that I found somewhere in the internet, to
> compute DCT for each 8x8 block in an gray (2D) image (512x512).
> 
> This is the code:
> 
> def dct2(a):
>     return
> scipy.fft.dct(scipy.fft.dct(a,axis=0,norm='ortho'),axis=1,norm='ortho')
> 
> imsize=im.shape
> dct=np.zeros(imsize)
> 
> # Do 8x8 DCT on image (in-place)
> for i in r_[:imsize[0]:8]: # Seems the same as "for i in
> np.arange(0,imsize[0],8)"!
>     for j in r_[:imsize[1]:8]:
>         dct[i:(i+8),j:(j+8)]=dct2(im[i:(i+8),j:(j+8)])
> 
> I tried to do the same thing with:
> 
> imsize=im.shape
> im8=im.reshape(imsize[0]*imsize[1]//8//8,8,8)
> dct_test=np.asarray([dct2(im8x) for im8x in im8])
> dct_test=dct_test.reshape(imsize)
> 
> so that dct_test should be equal to (previous) dct.
> But they are completely different.
> 
> What am I doing wrong?
> 
This was silly :-)
The first code splits the image in 8x8 squares.
The last one builds 8x8 squares from each line in sequence!

Forget this please.
Thanks.

From bgailer at gmail.com  Wed Dec  9 13:34:47 2020
From: bgailer at gmail.com (Bob Gailer)
Date: Wed, 9 Dec 2020 13:34:47 -0500
Subject: Unable to download
In-Reply-To: <CA+X5SuwFatkzD9ePCQn9ccECgK_WCKyAxkZswY+vk33hMKoJuw@mail.gmail.com>
References: <CA+X5SuwFatkzD9ePCQn9ccECgK_WCKyAxkZswY+vk33hMKoJuw@mail.gmail.com>
Message-ID: <CAP1rxO7oEaCb7nwBFvpQz3pD+Zqo3rOSccJt4gLhPow_U3Y4Ow@mail.gmail.com>

On Wed, Dec 9, 2020, 11:46 AM Siddarth Adiga <siddarthadiga at gmail.com>
wrote:

> Hello. I wanted to download the Python Version 3.9.1 but it said there was
> already another version of Python already installed. But I have deleted the
> program from the ADD OR REMOVE PROGRAMS option. But still I am unable to
> download it. Please help.


What OS are you using?

Exactly what did you do to download?
Exactly what did the error.message say?

Bob Gailer

>

From PythonList at DancesWithMice.info  Wed Dec  9 13:49:31 2020
From: PythonList at DancesWithMice.info (dn)
Date: Thu, 10 Dec 2020 07:49:31 +1300
Subject: Property type hints?
In-Reply-To: <c6ca926e6a53320e1c0f55bc082fa9644c9e93ab.camel@anode.ca>
References: <c6ca926e6a53320e1c0f55bc082fa9644c9e93ab.camel@anode.ca>
Message-ID: <3802dbe9-3783-ae69-4e71-84a4be00edb2@DancesWithMice.info>

On 09/12/2020 13:17, Paul Bryan wrote:
> Would this be a reasonably correct way to annotate a property with a
> type hint?
> 
>>>> class Foo:
> ...     bar: int


If we build a class with (only) the above two lines, Python's help 
lookup offers the following documentation:

<<<
Help on Foo in module __main__ object:

class Foo(builtins.object)
  |  Data descriptors defined here:
  |
  |  __dict__
  |      dictionary for instance variables (if defined)
  |
  |  __weakref__
  |      list of weak references to the object (if defined)
  |
  |  ----------------------------------------------------------------------
  |  Data and other attributes defined here:
  |
  |  __annotations__ = {'bar': <class 'int'>}
 >>>

Note the last line identifying 'bar' as having integer-type.

However, when we continue, by adding a property/lookup-method called 'bar'.

> ...     @property
> ...     def bar(self):
> ...         return 1


...the help lookup becomes:

<<<
class Foo(builtins.object)
  |  Readonly properties defined here:
  |
  |  bar
  |
  |  ----------------------------------------------------------------------
  |  Data descriptors defined here:
  |
  |  __dict__
  |      dictionary for instance variables (if defined)
  |
  |  __weakref__
  |      list of weak references to the object (if defined)
  |
  |  ----------------------------------------------------------------------
  |  Data and other attributes defined here:
  |
  |  __annotations__ = {'bar': <class 'int'>}
 >>>

Note that 'bar' has now been listed as a read-only property.

Further, if we remove the explicit typing (int) of 'bar', the help 
listing doesn't change.


<<<
class Foo(builtins.object)
  |  Readonly properties defined here:
  |
  |  bar
  |
  |  ----------------------------------------------------------------------
  |  Data descriptors defined here:
  |
  |  __dict__
  |      dictionary for instance variables (if defined)
  |
  |  __weakref__
  |      list of weak references to the object (if defined)
 >>>

Except that the annotation documentation has disappeared!

Hence, one assumes, the question!

The problem is that the help system appears to be talking about two 
different things: 'bar' the class int, and 'bar' the method/property. At 
run-time however, there cannot be two uses of the same name, and the 
last-defined 'wins'.

Continuing:-

> ...
>>>> foo = Foo()
>>>> import typing
>>>> typing.get_type_hints(foo)
> {'bar': <class 'int'>}
> 
> I could also decorate the property method return value:
> ...     def bar(self) -> int:

...and when the typing-hint is added to the property's def, the help 
listing still doesn't change/improve.


That said, I've been following this last convention since moving to typing.

Putting a separate description at the beginning of the class invites the 
reader to think of 'foo' as an integer. That's not 'wrong', in the sense 
that a property is/produces an attribute in the same dotted-notation 
from the object-name. However,there could be quite a lot of code between 
this 'declaration' line and the property def!

However, there is another line of logic built upon the idea that all 
class-attributes should be defined in the class 'header' and all 
instance-attributes in __init__() or __post_init__(). Does this underlie 
the discussion?


> I don't see the point though, because you can't access it with get_type_hints.

Correct: if one codes (only) the property-bar, then:

 >>> get_type_hints( Foo )
{}

However, reverting back to the first class-definition, we do see 
something for our money:

 >>> get_type_hints( foo )
{'bar': <class 'int'>}

Unfortunately, as mentioned above, there is this confusion between the 
two 'bar's...

Proof?

If we change things, the result is not what (it would appear) is desired:

 >>> class Foo:
...   bar:str
...   @property
...   def bar( self ):
...     return 1
...
 >>> get_type_hints( Foo )
{'bar': <class 'str'>}

Yet the 'bar' property will return an int!

...and this is proven/made worse when we add explicit typing to the 
property definition:

 >>> class Foo:
...   bar:str
...   @property
...   def bar( self )->int:
...     return 1
...
 >>> get_type_hints( Foo )
{'bar': <class 'str'>}

Our documentation entries don't agree, and don't match 'reality'. Ouch!

Beyond that, I won't hazard a guess at the minds of the 'Python gods' 
who design and implement these things. However, please remember that in 
this discussion we have been using Python itself, whereas the docs and 
PEP-justifications for typing clearly say:

<<<
Note The Python runtime does not enforce function and variable type 
annotations. They can be used by third party tools such as type 
checkers, IDEs, linters, etc.
 >>>

which may stump whatever the aim in using get-type-hints() may have been.


If we're only talking about code-review, then (personal) comment of 
'documenting' the method-definition applies.
-- 
Regards =dn

From pbryan at anode.ca  Wed Dec  9 19:06:03 2020
From: pbryan at anode.ca (Paul Bryan)
Date: Wed, 09 Dec 2020 16:06:03 -0800
Subject: Property type hints?
In-Reply-To: <3802dbe9-3783-ae69-4e71-84a4be00edb2@DancesWithMice.info>
References: <c6ca926e6a53320e1c0f55bc082fa9644c9e93ab.camel@anode.ca>
 <3802dbe9-3783-ae69-4e71-84a4be00edb2@DancesWithMice.info>
Message-ID: <5b5dc1a35ca16d061468abfcb5e0c87d2b2dc33d.camel@anode.ca>

Thanks for the comprehensive response, dn!

I guess I'm influenced by data classes here, where the object's
attribute type hints are represented by class variable annotations.


On Thu, 2020-12-10 at 07:49 +1300, dn via Python-list wrote:
> On 09/12/2020 13:17, Paul Bryan wrote:
> > Would this be a reasonably correct way to annotate a property with
> > a
> > type hint?
> > 
> > > > > class Foo:
> > ...???? bar: int
> 
> 
> If we build a class with (only) the above two lines, Python's help 
> lookup offers the following documentation:
> 
> <<<
> Help on Foo in module __main__ object:
> 
> class Foo(builtins.object)
> ? |? Data descriptors defined here:
> ? |
> ? |? __dict__
> ? |????? dictionary for instance variables (if defined)
> ? |
> ? |? __weakref__
> ? |????? list of weak references to the object (if defined)
> ? |
> ? |? ----------------------------------------------------------------
> ------
> ? |? Data and other attributes defined here:
> ? |
> ? |? __annotations__ = {'bar': <class 'int'>}
> ?>>>
> 
> Note the last line identifying 'bar' as having integer-type.
> 
> However, when we continue, by adding a property/lookup-method called
> 'bar'.
> 
> > ...???? @property
> > ...???? def bar(self):
> > ...???????? return 1
> 
> 
> ...the help lookup becomes:
> 
> <<<
> class Foo(builtins.object)
> ? |? Readonly properties defined here:
> ? |
> ? |? bar
> ? |
> ? |? ----------------------------------------------------------------
> ------
> ? |? Data descriptors defined here:
> ? |
> ? |? __dict__
> ? |????? dictionary for instance variables (if defined)
> ? |
> ? |? __weakref__
> ? |????? list of weak references to the object (if defined)
> ? |
> ? |? ----------------------------------------------------------------
> ------
> ? |? Data and other attributes defined here:
> ? |
> ? |? __annotations__ = {'bar': <class 'int'>}
> ?>>>
> 
> Note that 'bar' has now been listed as a read-only property.
> 
> Further, if we remove the explicit typing (int) of 'bar', the help 
> listing doesn't change.
> 
> 
> <<<
> class Foo(builtins.object)
> ? |? Readonly properties defined here:
> ? |
> ? |? bar
> ? |
> ? |? ----------------------------------------------------------------
> ------
> ? |? Data descriptors defined here:
> ? |
> ? |? __dict__
> ? |????? dictionary for instance variables (if defined)
> ? |
> ? |? __weakref__
> ? |????? list of weak references to the object (if defined)
> ?>>>
> 
> Except that the annotation documentation has disappeared!
> 
> Hence, one assumes, the question!
> 
> The problem is that the help system appears to be talking about two 
> different things: 'bar' the class int, and 'bar' the method/property.
> At 
> run-time however, there cannot be two uses of the same name, and the 
> last-defined 'wins'.
> 
> Continuing:-
> 
> > ...
> > > > > foo = Foo()
> > > > > import typing
> > > > > typing.get_type_hints(foo)
> > {'bar': <class 'int'>}
> > 
> > I could also decorate the property method return value:
> > ...???? def bar(self) -> int:
> 
> ...and when the typing-hint is added to the property's def, the help 
> listing still doesn't change/improve.
> 
> 
> That said, I've been following this last convention since moving to
> typing.
> 
> Putting a separate description at the beginning of the class invites
> the 
> reader to think of 'foo' as an integer. That's not 'wrong', in the
> sense 
> that a property is/produces an attribute in the same dotted-notation 
> from the object-name. However,there could be quite a lot of code
> between 
> this 'declaration' line and the property def!
> 
> However, there is another line of logic built upon the idea that all 
> class-attributes should be defined in the class 'header' and all 
> instance-attributes in __init__() or __post_init__(). Does this
> underlie 
> the discussion?
> 
> 
> > I don't see the point though, because you can't access it with
> > get_type_hints.
> 
> Correct: if one codes (only) the property-bar, then:
> 
> ?>>> get_type_hints( Foo )
> {}
> 
> However, reverting back to the first class-definition, we do see 
> something for our money:
> 
> ?>>> get_type_hints( foo )
> {'bar': <class 'int'>}
> 
> Unfortunately, as mentioned above, there is this confusion between
> the 
> two 'bar's...
> 
> Proof?
> 
> If we change things, the result is not what (it would appear) is
> desired:
> 
> ?>>> class Foo:
> ...?? bar:str
> ...?? @property
> ...?? def bar( self ):
> ...???? return 1
> ...
> ?>>> get_type_hints( Foo )
> {'bar': <class 'str'>}
> 
> Yet the 'bar' property will return an int!
> 
> ...and this is proven/made worse when we add explicit typing to the 
> property definition:
> 
> ?>>> class Foo:
> ...?? bar:str
> ...?? @property
> ...?? def bar( self )->int:
> ...???? return 1
> ...
> ?>>> get_type_hints( Foo )
> {'bar': <class 'str'>}
> 
> Our documentation entries don't agree, and don't match 'reality'.
> Ouch!
> 
> Beyond that, I won't hazard a guess at the minds of the 'Python gods'
> who design and implement these things. However, please remember that
> in 
> this discussion we have been using Python itself, whereas the docs
> and 
> PEP-justifications for typing clearly say:
> 
> <<<
> Note The Python runtime does not enforce function and variable type 
> annotations. They can be used by third party tools such as type 
> checkers, IDEs, linters, etc.
> ?>>>
> 
> which may stump whatever the aim in using get-type-hints() may have
> been.
> 
> 
> If we're only talking about code-review, then (personal) comment of 
> 'documenting' the method-definition applies.
> -- 
> Regards =dn


From siddarthadiga at gmail.com  Wed Dec  9 20:35:20 2020
From: siddarthadiga at gmail.com (Siddarth Adiga)
Date: Thu, 10 Dec 2020 07:05:20 +0530
Subject: Unable to download
In-Reply-To: <CAP1rxO7oEaCb7nwBFvpQz3pD+Zqo3rOSccJt4gLhPow_U3Y4Ow@mail.gmail.com>
References: <CA+X5SuwFatkzD9ePCQn9ccECgK_WCKyAxkZswY+vk33hMKoJuw@mail.gmail.com>
 <CAP1rxO7oEaCb7nwBFvpQz3pD+Zqo3rOSccJt4gLhPow_U3Y4Ow@mail.gmail.com>
Message-ID: <CA+X5SuxzUPY=qqz+LUzGi+R1w62ov25cppJWXzVKVXdBUFj7EA@mail.gmail.com>

Thank you for your concern. I use windows 10. But I was able to download
it. The fifth time I tried, it worked.
But then I had a prolem opening Jupyter Notebook, it said "Fatal error in
launcher: unable to create process using. The system cannot find the file
specified." So I had to download Anaconda.

So thank you. I was able to open Python.

On Thu, 10 Dec 2020, 00:04 Bob Gailer, <bgailer at gmail.com> wrote:

>
>
> On Wed, Dec 9, 2020, 11:46 AM Siddarth Adiga <siddarthadiga at gmail.com>
> wrote:
>
>> Hello. I wanted to download the Python Version 3.9.1 but it said there was
>> already another version of Python already installed. But I have deleted
>> the
>> program from the ADD OR REMOVE PROGRAMS option. But still I am unable to
>> download it. Please help.
>
>
> What OS are you using?
>
> Exactly what did you do to download?
> Exactly what did the error.message say?
>
> Bob Gailer
>
>>

From tjreedy at udel.edu  Wed Dec  9 21:13:44 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 9 Dec 2020 21:13:44 -0500
Subject: Python idle did not open even after trying many times
In-Reply-To: <CAP03=D4nsT+fkYOSuDaDiRoT50L1cEVZgj4e=4G-CtrB95u7gw@mail.gmail.com>
References: <CAP03=D4nsT+fkYOSuDaDiRoT50L1cEVZgj4e=4G-CtrB95u7gw@mail.gmail.com>
Message-ID: <rqs08p$l7u$1@ciao.gmane.io>

On 12/9/2020 11:08 AM, avinash gaur wrote:
> Dear Sir/Mam,
> I am facing a problem with Python Idle. I am unable to open python idle
> even after clicking on it so many times. I am using Python 3.7 on Windows.

What are you clicking on?
Did IDLE work before?  (If you just installed 3.7, why?)

Can you start interactive Python?  and get >>> prompt?
Does 'import tkinter' work?
Does 'import idlelib.idle' work?
-- 
Terry Jan Reedy


From PythonList at DancesWithMice.info  Thu Dec 10 01:13:08 2020
From: PythonList at DancesWithMice.info (dn)
Date: Thu, 10 Dec 2020 19:13:08 +1300
Subject: Property type hints?
In-Reply-To: <5b5dc1a35ca16d061468abfcb5e0c87d2b2dc33d.camel@anode.ca>
References: <c6ca926e6a53320e1c0f55bc082fa9644c9e93ab.camel@anode.ca>
 <3802dbe9-3783-ae69-4e71-84a4be00edb2@DancesWithMice.info>
 <5b5dc1a35ca16d061468abfcb5e0c87d2b2dc33d.camel@anode.ca>
Message-ID: <c8643ed3-965f-f745-d818-07cc8759f237@DancesWithMice.info>

On 10/12/2020 13:06, Paul Bryan wrote:
> Thanks for the comprehensive response, dn!
> 
> I guess I'm influenced by data classes here, where the object's 
> attribute type hints are represented by class variable annotations.


I'm a great fan of them too - the saving of 'boilerplate code' does it 
for me; but yes, the typing benefits come for-free!


Just in case it needs to be said: there's no need to 'declare' 
properties (or any other methods) as if they are class-attributes - 
either when using data-classes or rolling-your-own!

Also, remember that class-attributes will become (actually be 'hidden' 
by) instance-attributes if used on the LHS of an expression within the 
class (replicating the 'two' entity problem, discussed earlier).
-- 
Regards =dn

From PythonList at DancesWithMice.info  Fri Dec 11 13:22:21 2020
From: PythonList at DancesWithMice.info (dn)
Date: Sat, 12 Dec 2020 07:22:21 +1300
Subject: Planet Python
Message-ID: <76980276-ee36-47e2-5310-84211547cf70@etelligence.info>

Has something happened to the Planet Python feed?
- Last update: December 07, 2020 04:48 PM UTC
-- 
Regards,
=dn

From Bischoop at vimart.net  Fri Dec 11 20:25:12 2020
From: Bischoop at vimart.net (Bischoop)
Date: Sat, 12 Dec 2020 01:25:12 -0000 (UTC)
Subject: Function returns old value
Message-ID: <slrnrt86vo.517.Bischoop@vimart.net>




I've function asking question and comparing it, if is not matching 'yes'
it does call itself to ask question again. The problem is that when
function is called second time it returns old value or with additional
else statement it returns none.

Code: https://bpa.st/KVGA

How this functions should look properly?

--
Thanks in advance



From PythonList at DancesWithMice.info  Fri Dec 11 20:41:19 2020
From: PythonList at DancesWithMice.info (dn)
Date: Sat, 12 Dec 2020 14:41:19 +1300
Subject: Function returns old value
In-Reply-To: <slrnrt86vo.517.Bischoop@vimart.net>
References: <slrnrt86vo.517.Bischoop@vimart.net>
Message-ID: <68064583-3a43-2664-30fe-41093feabf9e@DancesWithMice.info>

On 12/12/2020 14:25, Bischoop wrote:
> 
> 
> 
> I've function asking question and comparing it, if is not matching 'yes'
> it does call itself to ask question again. The problem is that when
> function is called second time it returns old value or with additional
> else statement it returns none.
> 
> Code: https://bpa.st/KVGA
> 
> How this functions should look properly?


In the event of "yes" the function returns a value (return ask).
When the function calls itself, what happens to the return-ed value?
-- 
Regards =dn

From Bischoop at vimart.net  Fri Dec 11 20:48:45 2020
From: Bischoop at vimart.net (Bischoop)
Date: Sat, 12 Dec 2020 01:48:45 -0000 (UTC)
Subject: Letter replacer - suggestions?
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
 <0d1257d4-f665-dc14-0201-06eaa54c5ddf@mrabarnett.plus.com>
 <mailman.320.1607361312.7193.python-list@python.org>
Message-ID: <slrnrt88bt.517.Bischoop@vimart.net>

On 2020-12-07, MRAB <python at mrabarnett.plus.com> wrote:

> > word = input( f'input word you want to change letters in: ')

Yes, I've learn already that should use only when want to use variables
I just started using this new f' string method.

>
> There's no need for the f prefix.
>
> > print(f' Your word to change: ,{word}')
>
> Is the comma a typo?
>

lol mixing old and new methods, just old habit.

>
> > change_this_list = list(change_this)
> > replace_with_list = list(replace_with)
> >
> > while True:
> >     try:
> >         for element in word_list:
> >             for x in change_this_list:
> >                 if element == x:
> >                     to = word_list.index(element)
> >                     replace = change_this_list.index(x)
> >                     word_list[to] = replace_with_list[replace]
> >         new_word = ''.join(word_list)
> >         print(f'{new_word}')
>
>
> You can make it a lot shorter and faster by using a dict. The entire 
> while loop section can be replaced with:
>
> replacements = dict(zip(change_this, replace_with))
> new_word = ''.join(replacements.get(letter, letter) for letter in word)
> print(new_word


Simply and nice, I wouldn't come with that yet at all, beyond my
knowledge. Thanks a lot for feedback and suggestions.



From pfeiffer at cs.nmsu.edu  Fri Dec 11 20:55:43 2020
From: pfeiffer at cs.nmsu.edu (Joe Pfeiffer)
Date: Fri, 11 Dec 2020 18:55:43 -0700
Subject: Function returns old value
References: <slrnrt86vo.517.Bischoop@vimart.net>
Message-ID: <1bblezokio.fsf@pfeifferfamily.net>

Bischoop <Bischoop at vimart.net> writes:

> I've function asking question and comparing it, if is not matching 'yes'
> it does call itself to ask question again. The problem is that when
> function is called second time it returns old value or with additional
> else statement it returns none.
>
> Code: https://bpa.st/KVGA

It calls itself again, but what does it return in that case?

From Bischoop at vimart.net  Fri Dec 11 21:00:01 2020
From: Bischoop at vimart.net (Bischoop)
Date: Sat, 12 Dec 2020 02:00:01 -0000 (UTC)
Subject: Letter replacer - suggestions?
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
 <0d1257d4-f665-dc14-0201-06eaa54c5ddf@mrabarnett.plus.com>
 <rqlsnk$jh9$2@ciao.gmane.io>
 <CAPTjJmqxs=5VhSXv1tk=L5AmVimWBiidsjHhHgnKVuefNF-icg@mail.gmail.com>
 <mailman.329.1607370801.7193.python-list@python.org>
 <slrnrst2sc.55g.jon+usenet@raven.unequivocal.eu>
 <CAPTjJmq1A7YLD4Courvxyi_2Bk2C+Ht8jx6tOmR3QGdqXjpS5w@mail.gmail.com>
 <CABbU2U9oGa-x3+VFxpweoSfpN5Dk7XP7L+PEWHS6+WFHBkReLA@mail.gmail.com>
 <mailman.335.1607379436.7193.python-list@python.org>
Message-ID: <slrnrt8911.517.Bischoop@vimart.net>

On 2020-12-07, Marco Sulla <Marco.Sulla.Python at gmail.com> wrote:
> Not sure why you want to do this (it's schoolwork)?



>Anyway, this is my version:
>
Thanks, seems nicer I think not to mention those exceptions. 
So far I'm just learning and doing everythin only for myself so do not
think on others users but I know it's good to make a habit.


--
Thanks

From pbryan at anode.ca  Fri Dec 11 21:07:21 2020
From: pbryan at anode.ca (Paul Bryan)
Date: Fri, 11 Dec 2020 18:07:21 -0800
Subject: Function returns old value
In-Reply-To: <1bblezokio.fsf@pfeifferfamily.net>
References: <slrnrt86vo.517.Bischoop@vimart.net>
 <1bblezokio.fsf@pfeifferfamily.net>
Message-ID: <5b86074c9b1c34752373493add07136a62cba8b2.camel@anode.ca>

It won't return until the inner call to question (and it's not using
the return value on inner call). Eventually, (and not until you answer
yes) it will return the first answer.

On Fri, 2020-12-11 at 18:55 -0700, Joe Pfeiffer wrote:
> Bischoop <Bischoop at vimart.net> writes:
> 
> > I've function asking question and comparing it, if is not matching
> > 'yes'
> > it does call itself to ask question again. The problem is that when
> > function is called second time it returns old value or with
> > additional
> > else statement it returns none.
> > 
> > Code: https://bpa.st/KVGA
> 
> It calls itself again, but what does it return in that case?


From pbryan at anode.ca  Fri Dec 11 21:09:35 2020
From: pbryan at anode.ca (Paul Bryan)
Date: Fri, 11 Dec 2020 18:09:35 -0800
Subject: Function returns old value
In-Reply-To: <1bblezokio.fsf@pfeifferfamily.net>
References: <slrnrt86vo.517.Bischoop@vimart.net>
 <1bblezokio.fsf@pfeifferfamily.net>
Message-ID: <fc37116bfb7620936784a1dc106d67a56a2dde54.camel@anode.ca>

Sorry, actually, if you do not answer yes, will always return None, not
the first answer as I suggested.

On Fri, 2020-12-11 at 18:55 -0700, Joe Pfeiffer wrote:
> Bischoop <Bischoop at vimart.net> writes:
> 
> > I've function asking question and comparing it, if is not matching
> > 'yes'
> > it does call itself to ask question again. The problem is that when
> > function is called second time it returns old value or with
> > additional
> > else statement it returns none.
> > 
> > Code: https://bpa.st/KVGA
> 
> It calls itself again, but what does it return in that case?


From Bischoop at vimart.net  Fri Dec 11 21:09:15 2020
From: Bischoop at vimart.net (Bischoop)
Date: Sat, 12 Dec 2020 02:09:15 -0000 (UTC)
Subject: Function returns old value
References: <slrnrt86vo.517.Bischoop@vimart.net>
 <68064583-3a43-2664-30fe-41093feabf9e@DancesWithMice.info>
 <mailman.362.1607737293.7193.python-list@python.org>
Message-ID: <slrnrt89ib.517.Bischoop@vimart.net>

On 2020-12-12, dn <PythonList at DancesWithMice.info> wrote:
> On 12/12/2020 14:25, Bischoop wrote:
>> 
>> 
>> 
>> I've function asking question and comparing it, if is not matching 'yes'
>> it does call itself to ask question again. The problem is that when
>> function is called second time it returns old value or with additional
>> else statement it returns none.
>> 
>> Code: https://bpa.st/KVGA
>> 
>> How this functions should look properly?
>
>
> In the event of "yes" the function returns a value (return ask).
> When the function calls itself, what happens to the return-ed value?


Well I've put the output in a paste as well, anyway here is what is in a
paste:

def question():
    ask = input("Are you OK?:").lower()
        if ask != 'yes':
	        question()
		    return ask

		    print (question())

		    #output:
		    Are you OK?:no
		    Are you OK?:no
		    Are you OK?:yes
		    no

		    ---------------------------------------
		    #Another way with 'elif' statment returns none


		    def question():
		        ask = input("Are you OK?:").lower()
			    if ask != 'yes':
			            question()
				        elif ask == 'yes':
					        return ask

						print (question())

						#output:
						Are you OK?:no
						Are you OK?:yes
						None

						#Tried also nested
						functions, same results:

						def question():
						    ask = input("Are you
						    OK?:").lower()

						        def
							check_question(n):
							        if ask
								!=
								'yes':
								            question()
									            else:
										                return
												ask

												    m
												    =
												    check_question(ask)
												        print
													(m)
													question()

													#output:
													Are
													you
													OK?:no
													Are
													you
													OK?:yes
													None

													Process
													finished
													with
													exit
													code
													0


From Bischoop at vimart.net  Fri Dec 11 21:13:06 2020
From: Bischoop at vimart.net (Bischoop)
Date: Sat, 12 Dec 2020 02:13:06 -0000 (UTC)
Subject: Function returns old value
References: <slrnrt86vo.517.Bischoop@vimart.net>
 <1bblezokio.fsf@pfeifferfamily.net>
Message-ID: <slrnrt89pi.517.Bischoop@vimart.net>

On 2020-12-12, Joe Pfeiffer <pfeiffer at cs.nmsu.edu> wrote:
> Bischoop <Bischoop at vimart.net> writes:
>
>> I've function asking question and comparing it, if is not matching 'yes'
>> it does call itself to ask question again. The problem is that when
>> function is called second time it returns old value or with additional
>> else statement it returns none.
>>
>> Code: https://bpa.st/KVGA
>
> It calls itself again, but what does it return in that case?

I've stated it returns old value that I've input first time, anyway
output is also inluded in a paste but since you've asked:

def question():
    ask = input("Are you OK?:").lower()
        if ask != 'yes':
	        question()
		    return ask

		    print (question())

		    #output:
		    Are you OK?:no
		    Are you OK?:no
		    Are you OK?:yes
		    no

		    ---------------------------------------
		    #Another way with 'elif' statment returns none


		    def question():
		        ask = input("Are you OK?:").lower()
			    if ask != 'yes':
			            question()
				        elif ask == 'yes':
					        return ask

						print (question())

						#output:
						Are you OK?:no
						Are you OK?:yes
						None

						#Tried also nested
						functions, same results:

						def question():
						    ask = input("Are you
						    OK?:").lower()

						        def
							check_question(n):
							        if ask
								!=
								'yes':
								            question()
									            else:
										                return
												ask

												    m
												    =
												    check_question(ask)
												        print
													(m)
													question()

													#output:
													Are
													you
													OK?:no
													Are
													you
													OK?:yes
													None

													Process
													finished
													with
													exit
													code
													0


From PythonList at DancesWithMice.info  Fri Dec 11 21:21:29 2020
From: PythonList at DancesWithMice.info (dn)
Date: Sat, 12 Dec 2020 15:21:29 +1300
Subject: Function returns old value
In-Reply-To: <slrnrt89ib.517.Bischoop@vimart.net>
References: <slrnrt86vo.517.Bischoop@vimart.net>
 <68064583-3a43-2664-30fe-41093feabf9e@DancesWithMice.info>
 <mailman.362.1607737293.7193.python-list@python.org>
 <slrnrt89ib.517.Bischoop@vimart.net>
Message-ID: <39e7a344-168b-ee2e-45ec-c5ead771fbdc@DancesWithMice.info>

On 12/12/2020 15:09, Bischoop wrote:
> On 2020-12-12, dn <PythonList at DancesWithMice.info> wrote:
>> On 12/12/2020 14:25, Bischoop wrote:
>>>
>>>
>>>
>>> I've function asking question and comparing it, if is not matching 'yes'
>>> it does call itself to ask question again. The problem is that when
>>> function is called second time it returns old value or with additional
>>> else statement it returns none.
>>>
>>> Code: https://bpa.st/KVGA
>>>
>>> How this functions should look properly?
>>
>>
>> In the event of "yes" the function returns a value (return ask).
>> When the function calls itself, what happens to the return-ed value?

Apologies, the question was for you to ask yourself; not me asking for me!

When you read the code, to where are the results of the 'inner call' 
assigned?

If you can answer this question, you will solve 'the problem'!
(and have learned an approach to solving problems in-future)


> Well I've put the output in a paste as well, anyway here is what is in a
> paste:

Thank you.

Speaking personally, I prefer the code to be included in the email. 
However, it would be better to use spaces rather than tabs (Python's 
preferred style, per PEP-8) because many email packages implement 
tab-stops as eight-spaces apart.

-- 
Regards =dn

From rosuav at gmail.com  Fri Dec 11 21:25:26 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 12 Dec 2020 13:25:26 +1100
Subject: Function returns old value
In-Reply-To: <39e7a344-168b-ee2e-45ec-c5ead771fbdc@DancesWithMice.info>
References: <slrnrt86vo.517.Bischoop@vimart.net>
 <68064583-3a43-2664-30fe-41093feabf9e@DancesWithMice.info>
 <mailman.362.1607737293.7193.python-list@python.org>
 <slrnrt89ib.517.Bischoop@vimart.net>
 <39e7a344-168b-ee2e-45ec-c5ead771fbdc@DancesWithMice.info>
Message-ID: <CAPTjJmqTNoz76TV977nf0+LtQrFdoe5HS_2vAnGizjYN-UXPkA@mail.gmail.com>

On Sat, Dec 12, 2020 at 1:23 PM dn via Python-list
<python-list at python.org> wrote:
>
> Speaking personally, I prefer the code to be included in the email.
> However, it would be better to use spaces rather than tabs (Python's
> preferred style, per PEP-8) because many email packages implement
> tab-stops as eight-spaces apart.
>

Be careful of wording here. PEP 8 does not specify that all Python
code should use spaces rather than tabs. Tabs are absolutely fine for
your code.

ChrisA

From PythonList at DancesWithMice.info  Fri Dec 11 21:38:06 2020
From: PythonList at DancesWithMice.info (dn)
Date: Sat, 12 Dec 2020 15:38:06 +1300
Subject: Function returns old value
In-Reply-To: <CAPTjJmqTNoz76TV977nf0+LtQrFdoe5HS_2vAnGizjYN-UXPkA@mail.gmail.com>
References: <slrnrt86vo.517.Bischoop@vimart.net>
 <68064583-3a43-2664-30fe-41093feabf9e@DancesWithMice.info>
 <mailman.362.1607737293.7193.python-list@python.org>
 <slrnrt89ib.517.Bischoop@vimart.net>
 <39e7a344-168b-ee2e-45ec-c5ead771fbdc@DancesWithMice.info>
 <CAPTjJmqTNoz76TV977nf0+LtQrFdoe5HS_2vAnGizjYN-UXPkA@mail.gmail.com>
Message-ID: <4733a888-bd34-9528-293c-7b640b2c014e@DancesWithMice.info>

On 12/12/2020 15:25, Chris Angelico wrote:
> On Sat, Dec 12, 2020 at 1:23 PM dn via Python-list
> <python-list at python.org> wrote:
>>
>> Speaking personally, I prefer the code to be included in the email.
>> However, it would be better to use spaces rather than tabs (Python's
>> preferred style, per PEP-8) because many email packages implement
>> tab-stops as eight-spaces apart.
>>
> 
> Be careful of wording here. PEP 8 does not specify that all Python
> code should use spaces rather than tabs. Tabs are absolutely fine for
> your code.

Hence "preferred", cf "prescribed" or "required".

My personal reaction when ppl do make such a demand, is to use the 
facility built-in to decent editors/IDEs to change from one to the other 
- no fuss, no muss; peace reigns amongst the team once again...!

Wish could do that with such ease in other applications!

Nevertheless, email-client observation applies...
-- 
Regards =dn

From rosuav at gmail.com  Fri Dec 11 21:47:54 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 12 Dec 2020 13:47:54 +1100
Subject: Function returns old value
In-Reply-To: <4733a888-bd34-9528-293c-7b640b2c014e@DancesWithMice.info>
References: <slrnrt86vo.517.Bischoop@vimart.net>
 <68064583-3a43-2664-30fe-41093feabf9e@DancesWithMice.info>
 <mailman.362.1607737293.7193.python-list@python.org>
 <slrnrt89ib.517.Bischoop@vimart.net>
 <39e7a344-168b-ee2e-45ec-c5ead771fbdc@DancesWithMice.info>
 <CAPTjJmqTNoz76TV977nf0+LtQrFdoe5HS_2vAnGizjYN-UXPkA@mail.gmail.com>
 <4733a888-bd34-9528-293c-7b640b2c014e@DancesWithMice.info>
Message-ID: <CAPTjJmo97PR=TfUUjRrx-8w1fBENeF2C7J=gzdW5H+Hj5JWmyA@mail.gmail.com>

On Sat, Dec 12, 2020 at 1:39 PM dn via Python-list
<python-list at python.org> wrote:
>
> On 12/12/2020 15:25, Chris Angelico wrote:
> > On Sat, Dec 12, 2020 at 1:23 PM dn via Python-list
> > <python-list at python.org> wrote:
> >>
> >> Speaking personally, I prefer the code to be included in the email.
> >> However, it would be better to use spaces rather than tabs (Python's
> >> preferred style, per PEP-8) because many email packages implement
> >> tab-stops as eight-spaces apart.
> >>
> >
> > Be careful of wording here. PEP 8 does not specify that all Python
> > code should use spaces rather than tabs. Tabs are absolutely fine for
> > your code.
>
> Hence "preferred", cf "prescribed" or "required".

It's not even that. It's required for the standard library, and not at
all a language recommendation elsewhere.

> My personal reaction when ppl do make such a demand, is to use the
> facility built-in to decent editors/IDEs to change from one to the other
> - no fuss, no muss; peace reigns amongst the team once again...!
>
> Wish could do that with such ease in other applications!

Ah yes, and then you have these massive source control diffs when you
do a meaningless conversion over large slabs of the code! Perfect,
just what we wanted.

For teams that disagree on the correct width of indentation levels,
why not standardize on a single token meaning "indentation level", and
then allow everyone to configure their editors to show it at whatever
width they prefer?

> Nevertheless, email-client observation applies...

Yes. Make sure you use an email client that supports leading
whitespace of all forms. Otherwise you're not going to have a good
time of it.

ChrisA

From Bischoop at vimart.net  Fri Dec 11 20:49:58 2020
From: Bischoop at vimart.net (Bischoop)
Date: Sat, 12 Dec 2020 01:49:58 -0000 (UTC)
Subject: Letter replacer - suggestions?
References: <slrnrssjmb.3oh.Bischoop@vimart.net>
 <0d1257d4-f665-dc14-0201-06eaa54c5ddf@mrabarnett.plus.com>
 <rqlsnk$jh9$2@ciao.gmane.io>
 <mailman.327.1607369772.7193.python-list@python.org>
Message-ID: <slrnrt88e6.517.Bischoop@vimart.net>

On 2020-12-07, Grant Edwards <grant.b.edwards at gmail.com> wrote:
> On 2020-12-07, MRAB <python at mrabarnett.plus.com> wrote:
>
>> Avoid a 'bare' except unless you _really_ mean it, which is
>> virtually never. Catch only those exceptions that you're going to
>> handle.
>
> And sometimes "handling" is just printing some extra stuff and then
> re-raising the original exception:
>
>     try:
>         something():
>     except:
>         print(<whatever might be helpful for troubleshooting>)
>         raise
>
>

Noted, thanks.

From tjreedy at udel.edu  Fri Dec 11 20:59:07 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Fri, 11 Dec 2020 20:59:07 -0500
Subject: Function returns old value
In-Reply-To: <slrnrt86vo.517.Bischoop@vimart.net>
References: <slrnrt86vo.517.Bischoop@vimart.net>
Message-ID: <rr185b$136c$1@ciao.gmane.io>

On 12/11/2020 8:25 PM, Bischoop wrote:

> I've function asking question and comparing it, if is not matching 'yes'
> it does call itself to ask question again. The problem is that when
> function is called second time it returns old value or with additional
> else statement it returns none.
> 
> Code: https://bpa.st/??????

Don't post links to unknown sites.  Reduce it to the minimum needed to 
exhibit the questionable behavior and include inline with the question.

> How this functions should look properly?


-- 
Terry Jan Reedy


From ast at invalid  Sat Dec 12 01:39:49 2020
From: ast at invalid (ast)
Date: Sat, 12 Dec 2020 07:39:49 +0100
Subject: Returning from a multiple stacked call at once
Message-ID: <5fd465b5$0$8956$426a74cc@news.free.fr>

Hello

In case a function recursively calls itself many times,
is there a way to return a data immediately without
unstacking all functions ?


From cs at cskk.id.au  Sat Dec 12 03:18:25 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Sat, 12 Dec 2020 19:18:25 +1100
Subject: Returning from a multiple stacked call at once
In-Reply-To: <5fd465b5$0$8956$426a74cc@news.free.fr>
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
Message-ID: <20201212081825.GA17222@cskk.homeip.net>

On 12Dec2020 07:39, ast <ast at invalid> wrote:
>In case a function recursively calls itself many times,
>is there a way to return a data immediately without
>unstacking all functions ?

Not really. Do you have an example where this is inconvenient?

There are alternatives, for example passing in a Queue and put()ing the 
data onto the queue. It's quite dependent on what you're trying to do 
though.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From cs at cskk.id.au  Sat Dec 12 03:51:52 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Sat, 12 Dec 2020 19:51:52 +1100
Subject: Letter replacer - suggestions?
In-Reply-To: <slrnrt88e6.517.Bischoop@vimart.net>
References: <slrnrt88e6.517.Bischoop@vimart.net>
Message-ID: <20201212085152.GA23786@cskk.homeip.net>

On 12Dec2020 01:49, Bischoop <Bischoop at vimart.net> wrote:
>On 2020-12-07, Grant Edwards <grant.b.edwards at gmail.com> wrote:
>> On 2020-12-07, MRAB <python at mrabarnett.plus.com> wrote:
>>> Avoid a 'bare' except unless you _really_ mean it, which is
>>> virtually never. Catch only those exceptions that you're going to
>>> handle.
>>
>> And sometimes "handling" is just printing some extra stuff and then
>> re-raising the original exception:
>>
>>     try:
>>         something():
>>     except:
>>         print(<whatever might be helpful for troubleshooting>)
>>         raise
>
>Noted, thanks.

Also note that the exception itself is very interesting. So:

    except Exception as e:
        print(<whatever might be helpful for troubleshooting>, e)
        raise

Cheers,
Cameron Simpson <cs at cskk.id.au>

From jornws200602 at xs4all.nl  Sat Dec 12 10:59:31 2020
From: jornws200602 at xs4all.nl (Oscar)
Date: 12 Dec 2020 15:59:31 GMT
Subject: To check if number is in range(x,y)
References: <slrnrt9neo.40a.Bischoop@vimart.net>
 <slrnrt9otc.40a.Bischoop@vimart.net>
Message-ID: <5fd4e8e3$0$301$e4fe514c@news.xs4all.nl>

In article <slrnrt9otc.40a.Bischoop at vimart.net>,
Bischoop  <bischoop at gemail.com> wrote:
>I've also convert the choice to int() but doesn't help.

Oh.. did not read this yet. How did you do this? In both places after
the input or during the comparison? If so, in which version? Only the
first version would work. The other two are just plain wrong.
-- 
[J|O|R] <- .signature.gz

From Bischoop at vimart.net  Sat Dec 12 11:03:07 2020
From: Bischoop at vimart.net (Bischoop)
Date: Sat, 12 Dec 2020 16:03:07 -0000 (UTC)
Subject: To check if number is in range(x,y)
References: <slrnrt9neo.40a.Bischoop@vimart.net>
 <slrnrt9otc.40a.Bischoop@vimart.net>
 <5fd4e8e3$0$301$e4fe514c@news.xs4all.nl>
Message-ID: <slrnrt9qdr.40a.Bischoop@vimart.net>

On 2020-12-12, Oscar <jornws200602 at xs4all.nl> wrote:
> In article <slrnrt9otc.40a.Bischoop at vimart.net>,
> Bischoop  <bischoop at gemail.com> wrote:
>>I've also convert the choice to int() but doesn't help.
>
> Oh.. did not read this yet. How did you do this? In both places after
> the input or during the comparison? If so, in which version? Only the
> first version would work. The other two are just plain wrong.

after the input, https://bpa.st/BFJA

From jornws200602 at xs4all.nl  Sat Dec 12 11:10:46 2020
From: jornws200602 at xs4all.nl (Oscar)
Date: 12 Dec 2020 16:10:46 GMT
Subject: Returning from a multiple stacked call at once
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
Message-ID: <5fd4eb86$0$301$e4fe514c@news.xs4all.nl>

In article <5fd465b5$0$8956$426a74cc at news.free.fr>, ast  <ast at invalid> wrote:
>Hello
>
>In case a function recursively calls itself many times,
>is there a way to return a data immediately without
>unstacking all functions ?

If you are referring to your "are you ok?" problem, please read up on
recursion and when and how to use it. You were doing it completely
wrong. You only call a function from *whitin itself* if you need
recursion. It's quite hard to explain in a few words, so just google it.
I'm sure there are many great explanations around.
-- 
[J|O|R] <- .signature.gz

From Bischoop at vimart.net  Sat Dec 12 10:12:25 2020
From: Bischoop at vimart.net (Bischoop)
Date: Sat, 12 Dec 2020 15:12:25 -0000 (UTC)
Subject: To check if number is in range(x,y)
Message-ID: <slrnrt9neo.40a.Bischoop@vimart.net>


I need to check if input number is 1-5. Whatever I try it's not working.
Here are my aproaches to the problem: https://bpa.st/H62A

What I'm doing wrong and how I should do it?

--
Thanks

From Bischoop at vimart.net  Sat Dec 12 10:37:17 2020
From: Bischoop at vimart.net (Bischoop)
Date: Sat, 12 Dec 2020 15:37:17 -0000 (UTC)
Subject: To check if number is in range(x,y)
References: <slrnrt9neo.40a.Bischoop@vimart.net>
Message-ID: <slrnrt9otc.40a.Bischoop@vimart.net>


I've also convert the choice to int() but doesn't help.

From jornws200602 at xs4all.nl  Sat Dec 12 10:57:42 2020
From: jornws200602 at xs4all.nl (Oscar)
Date: 12 Dec 2020 15:57:42 GMT
Subject: To check if number is in range(x,y)
References: <slrnrt9neo.40a.Bischoop@vimart.net>
Message-ID: <5fd4e876$0$301$e4fe514c@news.xs4all.nl>

In article <slrnrt9neo.40a.Bischoop at vimart.net>,
Bischoop  <bischoop at gemail.com> wrote:
>
>I need to check if input number is 1-5. Whatever I try it's not working.
>Here are my aproaches to the problem: https://bpa.st/H62A
>
>What I'm doing wrong and how I should do it?

You need to learn about types. ;-)

Input returns a string. That string is not in the range you compare it
to. You need to convert it to an int:

choice = int(input.. )

This is assuming you want a whole number. You compare it against the
list of numbers [1, 2, 3, 4, 5]. If 2.4 is also a valid number, you need
a different comparison. 2.4 is not in this list. 

So first you should get your requirements straight.. ;-)
-- 
[J|O|R] <- .signature.gz

From Bischoop at vimart.net  Sat Dec 12 11:02:02 2020
From: Bischoop at vimart.net (Bischoop)
Date: Sat, 12 Dec 2020 16:02:02 -0000 (UTC)
Subject: To check if number is in range(x,y)
References: <slrnrt9neo.40a.Bischoop@vimart.net>
 <slrnrt9otc.40a.Bischoop@vimart.net>
Message-ID: <slrnrt9qbq.40a.Bischoop@vimart.net>


Got it solved here: https://bpa.st/BFJA

From ast at invalid  Sat Dec 12 11:46:33 2020
From: ast at invalid (ast)
Date: Sat, 12 Dec 2020 17:46:33 +0100
Subject: Returning from a multiple stacked call at once
In-Reply-To: <mailman.370.1607761505.7193.python-list@python.org>
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
 <20201212081825.GA17222@cskk.homeip.net>
 <mailman.370.1607761505.7193.python-list@python.org>
Message-ID: <5fd4f3ea$0$6469$426a74cc@news.free.fr>

Le 12/12/2020 ? 09:18, Cameron Simpson a ?crit?:
> On 12Dec2020 07:39, ast <ast at invalid> wrote:
>> In case a function recursively calls itself many times,
>> is there a way to return a data immediately without
>> unstacking all functions ?
> 
> Not really. Do you have an example where this is inconvenient?
> 
> There are alternatives, for example passing in a Queue and put()ing the
> data onto the queue. It's quite dependent on what you're trying to do
> though.
> 
> Cheers,
> Cameron Simpson <cs at cskk.id.au>
> 

I don't really need it. I was just wondering and guessed it was
not feasible.

Here is a code where it would be useful. This code looks for a
path in a graph.
If the found path is long, say 100 nodes, then path_finder calls
itself recursively 100 times, and has to unstack 100 times to
provide the found path. It could be returned immediately.


def path_finder(graph, start, end, path=[]):	

	if start in path:
		return None
	if start == end:
		return path + [start]   # Found !
	if start not in graph:
		return None
	
	path = path + [start]

	for node in graph[start]:
		found_path = path_finder(graph, node, end, path)
		if found_path:
			return found_path
	return None

graph = {'A': ['B', 'C'],
              'B': ['C', 'D'],
              'C': ['D'],
              'D': ['C'],
              'E': ['F'],
              'F': ['C']}

path_finder(graph, 'A', 'D')

From ast at invalid  Sat Dec 12 11:49:56 2020
From: ast at invalid (ast)
Date: Sat, 12 Dec 2020 17:49:56 +0100
Subject: Returning from a multiple stacked call at once
In-Reply-To: <5fd4eb86$0$301$e4fe514c@news.xs4all.nl>
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
 <5fd4eb86$0$301$e4fe514c@news.xs4all.nl>
Message-ID: <5fd4f4b5$0$8928$426a74cc@news.free.fr>

Le 12/12/2020 ? 17:10, Oscar a ?crit?:
> In article <5fd465b5$0$8956$426a74cc at news.free.fr>, ast  <ast at invalid> wrote:
>> Hello
>>
>> In case a function recursively calls itself many times,
>> is there a way to return a data immediately without
>> unstacking all functions ?
> 
> If you are referring to your "are you ok?" problem, please read up on
> recursion and when and how to use it. You were doing it completely
> wrong. You only call a function from *whitin itself* if you need
> recursion. It's quite hard to explain in a few words, so just google it.
> I'm sure there are many great explanations around.
> 

not understood.

From python.list at tim.thechases.com  Sat Dec 12 11:37:50 2020
From: python.list at tim.thechases.com (Tim Chase)
Date: Sat, 12 Dec 2020 10:37:50 -0600
Subject: Returning from a multiple stacked call at once
In-Reply-To: <5fd465b5$0$8956$426a74cc@news.free.fr>
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
Message-ID: <20201212103750.52069d42@bigbox.attlocal.net>

On 2020-12-12 07:39, ast wrote:
> In case a function recursively calls itself many times,
> is there a way to return a data immediately without
> unstacking all functions ?

Not that I'm aware of.   If you use recursion (and AFAIK, Python
doesn't support tail-recursion), you pay all the pushes & pay all the
pops.

If you convert it to an iterative algorithm, you can bail early with
items still in the work queue:

  while queue:
    item = queue.get()
    if test(item):
      print(f"Found it, bailing early with {len(queue)} item(s)")
      break
    more = process(item)
    if more:
      queue.extend(more)

-tkc





From python.list at tim.thechases.com  Sat Dec 12 11:51:00 2020
From: python.list at tim.thechases.com (Tim Chase)
Date: Sat, 12 Dec 2020 10:51:00 -0600
Subject: To check if number is in range(x,y)
In-Reply-To: <slrnrt9neo.40a.Bischoop@vimart.net>
References: <slrnrt9neo.40a.Bischoop@vimart.net>
Message-ID: <20201212105100.68a7568e@bigbox.attlocal.net>

On 2020-12-12 15:12, Bischoop wrote:
> I need to check if input number is 1-5. Whatever I try it's not
> working. Here are my aproaches to the problem: https://bpa.st/H62A
> 
> What I'm doing wrong and how I should do it?

A range is similar to a list in that it contains just the numbers
listed:

  >>> r = range(10)
  >>> 2 in r
  True
  >>> 2.5 in r
  False
  >>> r = range(1, 10, 2)
  >>> 2 in r
  False
  >>> list(r)
  [1, 3, 5, 7, 9]

It also doesn't automatically convert from the string inputs you're
getting from the input() function:

  >>> s = "5"
  >>> s in r
  False
  >>> int(s) in r
  True

Additionally, note that the endpoint of the range is exclusive so

  >>> r = range(1, 10)
  >>> 10 in r
  False
  >>> list(r)
  [1, 2, 3, 4, 5, 6, 7, 8, 9]

If you want numeric-range checks, Python provides the lovely
double-comparison syntax:

  >>> x = 5
  >>> 2 < x < 10
  True
  >>> x = 5.5
  >>> 2 < x < 10
  True
  >>> s = "5"
  >>> 2 < s < 10
  Traceback?
  >>> 2 < int(s) < 10
  True

Hopefully this gives you the hints that you need to troubleshoot.

-tkc





From dieter at handshake.de  Sat Dec 12 12:20:17 2020
From: dieter at handshake.de (Dieter Maurer)
Date: Sat, 12 Dec 2020 18:20:17 +0100
Subject: Returning from a multiple stacked call at once
In-Reply-To: <5fd465b5$0$8956$426a74cc@news.free.fr>
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
Message-ID: <24532.64465.213850.33597@ixdm.fritz.box>

ast wrote at 2020-12-12 07:39 +0100:
>In case a function recursively calls itself many times,
>is there a way to return a data immediately without
>unstacking all functions ?

Python does not have "long jump"s (out of many functions, many loop
incarnations).
In some cases, you can use exceptions to emulate "long jump"s.

From avigross at verizon.net  Sat Dec 12 13:21:02 2020
From: avigross at verizon.net (Avi Gross)
Date: Sat, 12 Dec 2020 13:21:02 -0500
Subject: Returning from a multiple stacked call at once
In-Reply-To: <24532.64465.213850.33597@ixdm.fritz.box>
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
 <24532.64465.213850.33597@ixdm.fritz.box>
Message-ID: <012901d6d0b3$8ccf5650$a66e02f0$@verizon.net>

As always, it may be useful to know WHY the questioner wants to skip
intermediate functions already in progress and jump back to some unspecified
earlier level.

There is a reason why functions are "stacked" and there are data structures
that really may need to be unwound. But if the question is not about some
sort of "efficiency" or speed but about ways to write the code so once
something has been found, it can fairly directly return, that does have
answers.

Tail recursion is an example, sometimes real as in the function is overlaid
and there is no need to return and sometimes sort of simulated with overhead
remaining but it looks like it returned. 

If all the functions written are your own, then simply calling your next
function that you want to be the return value (from anywhere applicable in
the function, not just the end, is easy enough to write as:

	return(next_function(args))

It will still unwind but logically will act as if it just returns without
the need for the functions to be written with lots of if statements or
twisted logic so nothing much gets done after the right result is obtained. 

And, of course, there are exceptions. If you raise an exception that you
know will not be caught until you reach the level where you do catch it, you
can sort of sail through any of the functions between and bypass any logic
that might otherwise be there for a normal return.

Arguably it might be better to write your code carefully so upon success, it
unwinds easily and only in low probability cases look for an abrupt exit.

And for a really abrupt exit, there is a way to shut down the program very
abruptly perhaps even too abruptly.

-----Original Message-----
From: Python-list <python-list-bounces+avigross=verizon.net at python.org> On
Behalf Of Dieter Maurer
Sent: Saturday, December 12, 2020 12:20 PM
To: ast <ast at invalid>
Cc: python-list at python.org
Subject: Re: Returning from a multiple stacked call at once

ast wrote at 2020-12-12 07:39 +0100:
>In case a function recursively calls itself many times, is there a way 
>to return a data immediately without unstacking all functions ?

Python does not have "long jump"s (out of many functions, many loop
incarnations).
In some cases, you can use exceptions to emulate "long jump"s.
--
https://mail.python.org/mailman/listinfo/python-list


Scanned by McAfee and confirmed virus-free.	
Find out more here: https://bit.ly/2zCJMrO


From 2QdxY4RzWzUUiLuE at potatochowder.com  Sat Dec 12 13:13:55 2020
From: 2QdxY4RzWzUUiLuE at potatochowder.com (2QdxY4RzWzUUiLuE at potatochowder.com)
Date: Sat, 12 Dec 2020 12:13:55 -0600
Subject: To check if number is in range(x,y)
In-Reply-To: <20201212105100.68a7568e@bigbox.attlocal.net>
References: <slrnrt9neo.40a.Bischoop@vimart.net>
 <20201212105100.68a7568e@bigbox.attlocal.net>
Message-ID: <X9UIYzlW6UtCwoGu@scrozzle>

On 2020-12-12 at 10:51:00 -0600,
Tim Chase <python.list at tim.thechases.com> wrote:

> If you want numeric-range checks, Python provides the lovely
> double-comparison syntax:
> 
>   >>> x = 5
>   >>> 2 < x < 10
>   True

Not just numbers:

    >>> 'm' < 'n' < 'o'
    True

    >>> 'one' < 'one point five' < 'two'
    True

Okay, so the second one is a trap, but you get the idea.  ;-)

From pfeiffer at cs.nmsu.edu  Sat Dec 12 14:51:50 2020
From: pfeiffer at cs.nmsu.edu (Joe Pfeiffer)
Date: Sat, 12 Dec 2020 12:51:50 -0700
Subject: Function returns old value
References: <slrnrt86vo.517.Bischoop@vimart.net>
 <1bblezokio.fsf@pfeifferfamily.net>
 <slrnrt89pi.517.Bischoop@vimart.net>
Message-ID: <1beejuby5l.fsf@pfeifferfamily.net>

Bischoop <Bischoop at vimart.net> writes:

> On 2020-12-12, Joe Pfeiffer <pfeiffer at cs.nmsu.edu> wrote:
>> Bischoop <Bischoop at vimart.net> writes:
>>
>>> I've function asking question and comparing it, if is not matching 'yes'
>>> it does call itself to ask question again. The problem is that when
>>> function is called second time it returns old value or with additional
>>> else statement it returns none.
>>>
>>> Code: https://bpa.st/KVGA
>>
>> It calls itself again, but what does it return in that case?
>
> I've stated it returns old value that I've input first time, anyway
> output is also inluded in a paste but since you've asked:

Sorry, my question wasn't clear.  What I meant was, "in your return
statement, what are you returning"?

You need to be returning the value from the recursive call.

> def question():
>     ask = input("Are you OK?:").lower()
>         if ask != 'yes':
> 	        question()
> 		    return ask
>
> 		    print (question())
>
> 		    #output:
> 		    Are you OK?:no
> 		    Are you OK?:no
> 		    Are you OK?:yes
> 		    no
>
> 		    ---------------------------------------
> 		    #Another way with 'elif' statment returns none
>
>
> 		    def question():
> 		        ask = input("Are you OK?:").lower()
> 			    if ask != 'yes':
> 			            question()
> 				        elif ask == 'yes':
> 					        return ask
>
> 						print (question())
>
> 						#output:
> 						Are you OK?:no
> 						Are you OK?:yes
> 						None
>
> 						#Tried also nested
> 						functions, same results:
>
> 						def question():
> 						    ask = input("Are you
> 						    OK?:").lower()
>
> 						        def
> 							check_question(n):
> 							        if ask
> 								!=
> 								'yes':
> 								            question()
> 									            else:
> 										                return
> 												ask
>
> 												    m
> 												    =
> 												    check_question(ask)
> 												        print
> 													(m)
> 													question()
>
> 													#output:
> 													Are
> 													you
> 													OK?:no
> 													Are
> 													you
> 													OK?:yes
> 													None
>
> 													Process
> 													finished
> 													with
> 													exit
> 													code
> 													0

From PythonList at DancesWithMice.info  Sat Dec 12 15:33:18 2020
From: PythonList at DancesWithMice.info (dn)
Date: Sun, 13 Dec 2020 09:33:18 +1300
Subject: Returning from a multiple stacked call at once
In-Reply-To: <5fd4f3ea$0$6469$426a74cc@news.free.fr>
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
 <20201212081825.GA17222@cskk.homeip.net>
 <mailman.370.1607761505.7193.python-list@python.org>
 <5fd4f3ea$0$6469$426a74cc@news.free.fr>
Message-ID: <f4ff393a-e829-51a1-fc2e-798e633a61b5@DancesWithMice.info>

On 13/12/2020 05:46, ast wrote:
> Le 12/12/2020 ? 09:18, Cameron Simpson a ?crit?:
>> On 12Dec2020 07:39, ast <ast at invalid> wrote:
>>> In case a function recursively calls itself many times,
>>> is there a way to return a data immediately without
>>> unstacking all functions ?
>>
>> Not really. Do you have an example where this is inconvenient?
>>
>> There are alternatives, for example passing in a Queue and put()ing the
>> data onto the queue. It's quite dependent on what you're trying to do
>> though.
> 
> I don't really need it. I was just wondering and guessed it was
> not feasible.


[somewhat simplified]
The way Python handles recursion is to add a "frame" every time the 
function is called. The "frame" contains all the data-items for the 
function. Think of the frames as stacked on top of each other:

	frame n
	frame n+1
	frame n+2
	...

NB you can 'see' this when viewing an exception tracing its way from a 
deeply-nested function, to the function which called it, to the function 
which called that, etc.

This is how node-1's attributes are kept separate from node-2's. If you 
think that only the 'current frame' as being visible at any stage of the 
program's execution, it will suit our purposes for-now.

One effect of a "return" is to close the current frame (and to carry any 
return-value 'back' to the previous frame).

Per comment (below), if this function recurses 100 times, then there 
will be 100 frames. Accordingly, there need to be 100 returns to close 
each of those frames.

NB Python offers reflective facilities to inspect all of this, if you 
really want to see what happens 'under the hood/bonnet'.


> Here is a code where it would be useful. This code looks for a
> path in a graph.
> If the found path is long, say 100 nodes, then path_finder calls
> itself recursively 100 times, and has to unstack 100 times to
> provide the found path. It could be returned immediately.
 > ...

Recursion may not be the best tool/tactic here. As you observe, it has 
to be 'unwound'!

Assuming the objectives are:
1 trace through a graph
2 locate an identified node
3 note (and make available 'later') the path through the graph to reach 
said node.

The logic for (1) and (2) has been done.

For (3), consider using a "stack". This is a ComSc term (in case you've 
not studied such), and is the same concept as the 'stack of frames' (above).

1 Create a list "stack".
2 Walk the network.
3 Upon 'arrival' at a node, add the node to the 'stack' by appending 
relevant detail(s) to the list.
4 If the node is 'the end', stop walking.

If the 'walk' is a loop (cf recursion), the 'stop' becomes a (single) 
"break".

If the identified node is found 50-nodes 'in', or 100-nodes, that will 
be the length of the list/stack. (which BTW will require less storage 
than the same number of recursion-frames)

Now, back to ComSc (again, with apologies for appearing to 'talk-down', 
if you've studied this stuff but let's help anyone else 'following along 
at home'), when it comes to using the list/stack, if you start with the 
found-node and work your way 'back' to the start-node, this will require 
working from the list[ -1 ] element, back to the zero-th element. 
Accessing each element is known as "popping the stack", and you will 
find a Python list.method() enacting such - but be careful about the 
working-backwards logic!

Conversely, if the ensuing functionality wants to 'start' from the 
start-node and walk 'forward' through the graph to the found-node; then 
that process will start at list[ 0 ], per most collection-processing. In 
which case, rather than a "stack", we are looking at a "queue" (per 
@Cameron).

Thus, a "stack" accepts additions to 'the end', and "pops" data from the 
same 'end' ("LIFO" = last-in, first-out). Whereas a "queue" also adds to 
'the end', but processes/pops from the beginning ("FIFO" = first-in, 
first-out).

If this ComSc-stuff is 'new', then plenty of books and web-sites discuss 
such data-structures...
-- 
Regards =dn

From cs at cskk.id.au  Sat Dec 12 16:37:42 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Sun, 13 Dec 2020 08:37:42 +1100
Subject: Returning from a multiple stacked call at once
In-Reply-To: <5fd4f3ea$0$6469$426a74cc@news.free.fr>
References: <5fd4f3ea$0$6469$426a74cc@news.free.fr>
Message-ID: <20201212213742.GA67229@cskk.homeip.net>

On 12Dec2020 17:46, ast <ast at invalid> wrote:
>Le 12/12/2020 ? 09:18, Cameron Simpson a ?crit?:
>>On 12Dec2020 07:39, ast <ast at invalid> wrote:
>>>In case a function recursively calls itself many times,
>>>is there a way to return a data immediately without
>>>unstacking all functions ?
>>
>>Not really. Do you have an example where this is inconvenient?
>>There are alternatives, for example passing in a Queue and put()ing 
>>the data onto the queue.
[...]
>
>I don't really need it. I was just wondering and guessed it was
>not feasible.

Well, it is feasible. Kinda. Regardless, the stack need to unwind. You 
_could_ abuse exceptions to do that in a single go:

    class CompletedOperation(Exception):

        def __init__(self, value):
            self.value = value

    ... in your function ...
      raise CompletedOperation(the_value)

    ... at the calling end ...
    try:
        call_the_function(....)
    except CompletedOperation as e:
        value = e.value
    else:
        ... value not found ...

or obvious variations where that try/except it done by the outermost 
function invocation, concealing it from users.

But usually you just return the value from the innermost call and return 
that in turn:

    def f(....):
        for subpart in ... stuff ...:
            value = f(subpart)
            if value is not None:
                return value
        return None

which searches some data structure and returns nonNone on finding 
something, None if not found.

>Here is a code where it would be useful. This code looks for a
>path in a graph.
>If the found path is long, say 100 nodes, then path_finder calls
>itself recursively 100 times, and has to unstack 100 times to
>provide the found path. It could be returned immediately.

The above code returns efficiently. But there's a cascade of returns.

WRT to the below code, I thought I'd restate what DL Neil has said: you 
can often make these things nonrecursive by maintaining a queue or stack 
of pending tasks. A recursive function keeps it state in the call stack, 
but you needn't do that:

    def f(node,...):
        pending = [node]
        while pending:
            node = pending.pop(0)
            if node is the one you're looking for:
                return node
            pending.extend(children of the node here ...)
        return None

This keeps a queue of unexamined nodes in pending. You could make that a 
stack by replacing the .pop(0) with .pop(). That will be more efficient 
(remove the leading element of a list is comparatively expensive) but 
changes the search order.

Anyway, this is what DL Neil is referring to: a nonrecursive function 
with a data structure to hold the coming work, which a recursive 
function would process by calling itself instead of saving the undone 
task (chid nodes, here).

Cheers,
Cameron Simpson <cs at cskk.id.au>

From greg.ewing at canterbury.ac.nz  Sat Dec 12 18:52:50 2020
From: greg.ewing at canterbury.ac.nz (Greg Ewing)
Date: Sun, 13 Dec 2020 12:52:50 +1300
Subject: Returning from a multiple stacked call at once
In-Reply-To: <5fd4f3ea$0$6469$426a74cc@news.free.fr>
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
 <20201212081825.GA17222@cskk.homeip.net>
 <mailman.370.1607761505.7193.python-list@python.org>
 <5fd4f3ea$0$6469$426a74cc@news.free.fr>
Message-ID: <i3l3ekFt4huU1@mid.individual.net>

On 13/12/20 5:46 am, ast wrote:
> Here is a code where it would be useful. This code looks for a
> path in a graph.

Recursion is probably not the best way to solve this problem in
CPython, because it imposes a limit on the number of nested calls
(in order to detect runaway recursion). By default the limit is
about 1000. So if you have a large graph with a path more than
1000 steps long, you can hit the recursion limit.

-- 
Greg

From Bischoop at vimart.net  Sat Dec 12 19:01:43 2020
From: Bischoop at vimart.net (Bischoop)
Date: Sun, 13 Dec 2020 00:01:43 -0000 (UTC)
Subject: Unable to pass dict from json.
Message-ID: <slrnrtamf7.d49.Bischoop@vimart.net>


Here https://bpa.st/YBVA  I've working code with dictionary only if used dict from the code
(it's commented now) but when I load it I can print it from load
function (line 14)  but at all have not a
clue how to pass the data so could use them.
I've learnt a lot when making it but here I'm completetly stuck, was
trying do solve it for a whole day and it's just a death wall for me.

--
Thanks

From Bischoop at vimart.net  Sat Dec 12 17:57:48 2020
From: Bischoop at vimart.net (Bischoop)
Date: Sat, 12 Dec 2020 22:57:48 -0000 (UTC)
Subject: To check if number is in range(x,y)
References: <slrnrt9neo.40a.Bischoop@vimart.net>
 <20201212105100.68a7568e@bigbox.attlocal.net>
 <mailman.373.1607794732.7193.python-list@python.org>
Message-ID: <slrnrtainc.d49.Bischoop@vimart.net>

On 2020-12-12, Tim Chase <python.list at tim.thechases.com> wrote:
>
> Hopefully this gives you the hints that you need to troubleshoot.
>
> -tkc
>
>
>
>

Yes it explains a lot.

Thanks

From drsalists at gmail.com  Sat Dec 12 19:44:30 2020
From: drsalists at gmail.com (Dan Stromberg)
Date: Sat, 12 Dec 2020 16:44:30 -0800
Subject: Unable to pass dict from json.
In-Reply-To: <slrnrtamf7.d49.Bischoop@vimart.net>
References: <slrnrtamf7.d49.Bischoop@vimart.net>
Message-ID: <CAGGBd_rqdqEySX=Lkvp5mdmFkkQmrvbbX47Q+fALnmDPx42iaA@mail.gmail.com>

On Sat, Dec 12, 2020 at 4:05 PM Bischoop <Bischoop at vimart.net> wrote:

>
> Here https://bpa.st/YBVA  I've working code with dictionary only if used
> dict from the code
> (it's commented now) but when I load it I can print it from load
> function (line 14)  but at all have not a
> clue how to pass the data so could use them.
> I've learnt a lot when making it but here I'm completetly stuck, was
> trying do solve it for a whole day and it's just a death wall for me.
>

I too recommend cutting and pasting minimal code into your e-mail, instead
of referring to a URL; URL's used this way are a common attack vector.

From python at mrabarnett.plus.com  Sat Dec 12 19:54:09 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Sun, 13 Dec 2020 00:54:09 +0000
Subject: Unable to pass dict from json.
In-Reply-To: <slrnrtamf7.d49.Bischoop@vimart.net>
References: <slrnrtamf7.d49.Bischoop@vimart.net>
Message-ID: <d5a52fe9-0144-0350-671c-25e04240d1dd@mrabarnett.plus.com>

On 2020-12-13 00:01, Bischoop wrote:
> 
> Here https://bpa.st/YBVA  I've working code with dictionary only if used dict from the code
> (it's commented now) but when I load it I can print it from load
> function (line 14)  but at all have not a
> clue how to pass the data so could use them.
> I've learnt a lot when making it but here I'm completetly stuck, was
> trying do solve it for a whole day and it's just a death wall for me.
> 
It would be better to use a loop instead of recursion in load_options 
when asking for the choice.

load_json returns the data, so just have load_options return it and then 
pass it in to the functions that need it.

There's no need to make 'load_json' and the others local to 
'load_from_file', and similarly for save_tofile.

From jfong at ms4.hinet.net  Sat Dec 12 21:17:40 2020
From: jfong at ms4.hinet.net (Jach Feng)
Date: Sat, 12 Dec 2020 18:17:40 -0800 (PST)
Subject: To whom he want to set breakpoint on negative line number in pdb
Message-ID: <32c60cb3-8fdd-4c4b-b271-f05363440c2an@googlegroups.com>

I use .pdbrc file to help debugging. To avoid editing this file frequently when source was modified, I need this feature.

I modify the checkline function in pdb.py from
    ...
    line = linecache.getline(filename, lineno, globs)
    if not line:
        ....
to
    ...
    lines = linecache.getlines(filename, globs)
    if lineno < 0:  lineno = len(lines) + lineno + 1  # change to a valid positive number, or not
    if 1 <= lineno <= len(lines):  line = lines[lineno-1]
    else:  line = ''
    if not line:
        ...

This modification is mostly the copy of the getline function body except the added line. It will not influence the original pdb usage in anyway.

--Jach

From grant.b.edwards at gmail.com  Sat Dec 12 19:46:12 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Sun, 13 Dec 2020 00:46:12 -0000 (UTC)
Subject: Unable to pass dict from json.
References: <slrnrtamf7.d49.Bischoop@vimart.net>
Message-ID: <rr3o8k$113r$1@ciao.gmane.io>

On 2020-12-13, Bischoop <Bischoop at vimart.net> wrote:

> Here https://bpa.st/YBVA

Don't do that. Include in your post a short example that illustrates
your questions.

> I've working code with dictionary only if used dict from the code
> [...]


From ethan at stoneleaf.us  Sun Dec 13 12:54:20 2020
From: ethan at stoneleaf.us (Ethan Furman)
Date: Sun, 13 Dec 2020 09:54:20 -0800
Subject: Fwd: Fwd: How to specify JSON parameters in CallBack?
In-Reply-To: <CAN6f9eWPKJ_Ka88ZvC6HdQd=LjJ3hgdDbx2o6ZCt-1AbAdgM-g@mail.gmail.com>
References: <CAN6f9eWPKJ_Ka88ZvC6HdQd=LjJ3hgdDbx2o6ZCt-1AbAdgM-g@mail.gmail.com>
Message-ID: <e358ed06-5d9f-aae4-efb6-d50120b0c939@stoneleaf.us>

From: Caleb Gattegno
Date: Fri, Dec 11, 2020 at 5:02 PM
Subject: How to specify JSON parameters in CallBack?


Please can you suggest where should I look for advice on converting a old style web app which vends whole pages of html 
with a cgi-bin/python script invoked bypython3 server.py, into one that only serves callbacks to this Javascript AJAX 
async RPC call:

$('#compute').click(function() {
  ? ? $('#poly').val('Waiting...');

  ? ? var seq = $('#seq').val();
  ? ? console.log(seq);
  ? ? $.post('/compute', seq, function(result) {
  ? ? ? ? $('#poly').val(result.poly);
  ? ? }, 'json');
});

I don?t want to touch the html/javascript, but I?d like to update the python cgi code module to respond to the RPC call 
in the post by returning a json data structure. Poly is a string of variable length.

Many thanks
gattegnPython

From rosuav at gmail.com  Sun Dec 13 13:25:02 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 14 Dec 2020 05:25:02 +1100
Subject: Fwd: How to specify JSON parameters in CallBack?
In-Reply-To: <e358ed06-5d9f-aae4-efb6-d50120b0c939@stoneleaf.us>
References: <CAN6f9eWPKJ_Ka88ZvC6HdQd=LjJ3hgdDbx2o6ZCt-1AbAdgM-g@mail.gmail.com>
 <e358ed06-5d9f-aae4-efb6-d50120b0c939@stoneleaf.us>
Message-ID: <CAPTjJmozU7aRATJs06DQFt+oG26Hfvvc_JNjP9QTsRxbYLV1UA@mail.gmail.com>

On Mon, Dec 14, 2020 at 4:57 AM Ethan Furman <ethan at stoneleaf.us> wrote:
>
> From: Caleb Gattegno
> Date: Fri, Dec 11, 2020 at 5:02 PM
> Subject: How to specify JSON parameters in CallBack?
>
>
> Please can you suggest where should I look for advice on converting a old style web app which vends whole pages of html
> with a cgi-bin/python script invoked bypython3 server.py, into one that only serves callbacks to this Javascript AJAX
> async RPC call:
>
> $('#compute').click(function() {
>       $('#poly').val('Waiting...');
>
>       var seq = $('#seq').val();
>       console.log(seq);
>       $.post('/compute', seq, function(result) {
>           $('#poly').val(result.poly);
>       }, 'json');
> });
>
> I don?t want to touch the html/javascript, but I?d like to update the python cgi code module to respond to the RPC call
> in the post by returning a json data structure. Poly is a string of variable length.
>

First place to look would be a well-known server framework. I use
Flask, but there are others. Figure out exactly what your front end is
sending; use your web browser's developer tools to inspect the
requests, and then code your back end to match.

Writing a JSON-based API in Flask is pretty straight-forward. Here's an example:

@app.route("/api/widgets")
def list_setups():
    return jsonify(database.list_widgets())

@app.route("/api/widgets/<int:id>")
def get_widget(id):
    return jsonify(database.get_widget(id))

@app.route("/api/widgets", methods=["POST"])
def create_widget():
    if not request.json: return jsonify({}), 400
    missing = {"name", "purpose"} - set(request.json)
    if missing:
        return jsonify({"error": "Missing: " + ", ".join(sorted(missing))}), 400
    widget = database.create_widget(request.json["name"],
request.json["purpose"])
    return jsonify(widget)

(For a real example, see
https://github.com/Rosuav/MustardMine/blob/master/mustard.py#L643 -
although that has a lot of other complexities.)

ChrisA

From sh at changeset.nyc  Sun Dec 13 16:22:39 2020
From: sh at changeset.nyc (Sumana Harihareswara)
Date: Sun, 13 Dec 2020 16:22:39 -0500
Subject: pip 20.3 release (heads-up for potential disruption)
In-Reply-To: <5d8a1134-82a0-6c81-03f9-c8d9de9b21f4@changeset.nyc>
References: <5d8a1134-82a0-6c81-03f9-c8d9de9b21f4@changeset.nyc>
Message-ID: <d2ac9955-2da8-5dbd-929e-c98e77569458@changeset.nyc>

On 11/30/20 8:33 AM, Sumana Harihareswara wrote:
> On behalf of the Python Packaging Authority, I am pleased to announce 
> that we have just released pip 20.3, a new version of pip. You can 
> install it by running `python -m pip install --upgrade pip`.
> 
> This is an important and disruptive release -- we explained why in a
> blog post last year 
> https://pyfound.blogspot.com/2019/12/moss-czi-support-pip.html . We even 
> made a video about it: https://www.youtube.com/watch?v=B4GQCBBsuNU .
> 
> Blog post with details: 
> https://pyfound.blogspot.com/2020/11/pip-20-3-new-resolver.html
> 
> Highlights include:
> 
> * **DISRUPTION**: Switch to the new dependency resolver by
>  ??? default. Watch out for changes in handling editable
>  ??? installs, constraints files, and more:
> 
> https://pip.pypa.io/en/latest/user_guide/#changes-to-the-pip-dependency-resolver-in-20-3-2020 
> 
> 
> * **DEPRECATION**: Deprecate support for Python 3.5 (to be removed in
>  ??? pip 21.0)
> 
> * **DEPRECATION**: pip freeze will stop filtering the pip, setuptools,
>  ??? distribute and wheel packages from pip freeze output in a future
>  ??? version. To keep the previous behavior, users should use the new
>  ??? `--exclude` option.
> 
> * Support for PEP 600: Future ?manylinux? Platform Tags for Portable
>  ? Linux Built Distributions.
> 
> * Add support for MacOS Big Sur compatibility tags.
> 
> The new resolver is now *on by default*. It is significantly stricter
> and more consistent when it receives incompatible instructions, and
> reduces support for certain kinds of constraints files, so some
> workarounds and workflows may break. Please see our guide on how to
> test and migrate, and how to report issues: 
> https://pip.pypa.io/en/latest/user_guide/#changes-to-the-pip-dependency-resolver-in-20-3-2020 
> . You can use the deprecated (old) resolver, using the flag
> `--use-deprecated=legacy-resolver`, until we remove it in the pip 21.0
> release in January 2021.
> 
> In pip 21.0 we will also remove support for Python 2.7.
> 
> You can find more details (including deprecations and removals) in the
> changelog https://pip.pypa.io/en/stable/news/ , and you can find 
> thank-yous and instructions on reporting issues at 
> https://pyfound.blogspot.com/2020/11/pip-20-3-new-resolver.html .
> 
> Thank you,
> Sumana Harihareswara
> pip project manager
> Changeset Consulting
> https://changeset.nyc


Incidentally, I should have mentioned in my previous email:

pip 20.3 turned the new resolver on by default for Python 3 users. When 
users use pip 20.3 in a Python 2 environment, the old dependency 
resolver is still the default. Python 2 users should also note that pip 
21.0 in January will remove Python 2 support: 
https://pip.pypa.io/en/latest/development/release-process/#python-2-support 
.

-- 
Sumana Harihareswara


From jornws200602 at xs4all.nl  Sun Dec 13 16:41:41 2020
From: jornws200602 at xs4all.nl (Oscar)
Date: 13 Dec 2020 21:41:41 GMT
Subject: Returning from a multiple stacked call at once
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
 <5fd4eb86$0$301$e4fe514c@news.xs4all.nl>
 <5fd4f4b5$0$8928$426a74cc@news.free.fr>
Message-ID: <5fd68a95$0$305$e4fe514c@news.xs4all.nl>

In article <5fd4f4b5$0$8928$426a74cc at news.free.fr>, ast  <ast at invalid> wrote:
>Le 12/12/2020 ?? 17:10, Oscar a ??crit??:
>> In article <5fd465b5$0$8956$426a74cc at news.free.fr>, ast  <ast at invalid> wrote:
>>> Hello
>>>
>>> In case a function recursively calls itself many times,
>>> is there a way to return a data immediately without
>>> unstacking all functions ?
>> 
>> If you are referring to your "are you ok?" problem, please read up on
>> recursion and when and how to use it. You were doing it completely
>> wrong. You only call a function from *whitin itself* if you need
>> recursion. It's quite hard to explain in a few words, so just google it.
>> I'm sure there are many great explanations around.
>> 
>
>not understood.

I understand! Sorry...

Somehow I mixed you up with another poster that was clearly beginning
with programming and wrote an input function that called itself
recursively when it received invalid input. Then he was suprised the
calling function got the very first (invalid) value. 

You clearly know your way around recursion. Sorry again! ;-)
-- 
[J|O|R] <- .signature.gz

From PythonList at DancesWithMice.info  Mon Dec 14 13:08:30 2020
From: PythonList at DancesWithMice.info (dn)
Date: Tue, 15 Dec 2020 07:08:30 +1300
Subject: Planet Python
In-Reply-To: <76980276-ee36-47e2-5310-84211547cf70@etelligence.info>
References: <76980276-ee36-47e2-5310-84211547cf70@etelligence.info>
Message-ID: <d1a2bab4-f546-1297-6a88-be5d2da9fe25@DancesWithMice.info>

On 12/12/2020 07:22, dn via Python-list wrote:
> Has something happened to the Planet Python feed?
> - Last update: December 07, 2020 04:48 PM UTC


Fixed! (Thanks!)

Although, still reported as an 'open' issue
https://github.com/python/planet/issues/446
-- 
Regards =dn

From Joseph.Schachner at Teledyne.com  Mon Dec 14 16:21:43 2020
From: Joseph.Schachner at Teledyne.com (Schachner, Joseph)
Date: Mon, 14 Dec 2020 21:21:43 +0000
Subject: To check if number is in range(x,y)
In-Reply-To: <20201212105100.68a7568e@bigbox.attlocal.net>
References: <slrnrt9neo.40a.Bischoop@vimart.net>
 <20201212105100.68a7568e@bigbox.attlocal.net>
Message-ID: <BN8PR14MB28515D34591ADF2A5EBCC62EF5C70@BN8PR14MB2851.namprd14.prod.outlook.com>

>>> r = range(10)
So r is a list containing 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

  >>> 2 in r
  True
As expected.

  >>> 2.5 in r
  False
Also as expected.  If you did int(floor(2.5)) in 5 that would be true.

  >>> r = range(1, 10, 2)
  >>> 2 in r
  False
  >>> list(r)
  [1, 3, 5, 7, 9]
Well, yes, because you started the range at 1.  Start at 0 and you'd get 0, 2, 4, 6, 8.

"It also doesn't automatically convert from the string inputs you're getting from the input() function:

  >>> s = "5"
  >>> s in r
  False
  >>> int(s) in r
  True"
You have just discovered that Python, although it is dynamically typed, is STRICTLY typed.  Another way to say this: you have discovered that Python isn't the same as BASIC.  Yes, you have to convert strings to int or float, Python does not assume you want to if you did not do it. Similarly, you have to do something to convert int or float to text.  Python makes it very simple, but you have to do it.


"Additionally, note that the endpoint of the range is exclusive so
  >>> r = range(1, 10)
  >>> 10 in r
  False"

I don't have to note that, I KNOW that (as I've demonstrated above), because I read a couple of books on Python.  Python range starts on the number you specify and does NOT include the end number.
So: range(0,10) is 0 to 9    (note that this is 10 integers)
      range(10,20) is 10 to 19    (also 10 integers)
      range(20,30) is 20 to 29   (another 10 integers)

Now suppose that the end integer was not excluded. Each range call would produce 11 integers.  10, 20, and 30 would occur twice.  Or you'd have to set the range limits differently.

I recommend you read Python 101 and when you've done that, read Python 201.   I think they are very good "learn Python" books.
If you're surprised that the end point is not included in range, you need to read Python 101.

--- Joseph S.



-----Original Message-----
From: Tim Chase <python.list at tim.thechases.com>
Sent: Saturday, December 12, 2020 11:51 AM
To: Bischoop <Bischoop at vimart.net>
Cc: Bischoop <bischoop at gemail.com>; python-list at python.org
Subject: Re: To check if number is in range(x,y)

On 2020-12-12 15:12, Bischoop wrote:
> I need to check if input number is 1-5. Whatever I try it's not
> working. Here are my aproaches to the problem: https://bpa.st/H62A
>
> What I'm doing wrong and how I should do it?

A range is similar to a list in that it contains just the numbers
listed:

  >>> r = range(10)
  >>> 2 in r
  True
  >>> 2.5 in r
  False
  >>> r = range(1, 10, 2)
  >>> 2 in r
  False
  >>> list(r)
  [1, 3, 5, 7, 9]

It also doesn't automatically convert from the string inputs you're getting from the input() function:

  >>> s = "5"
  >>> s in r
  False
  >>> int(s) in r
  True

Additionally, note that the endpoint of the range is exclusive so

  >>> r = range(1, 10)
  >>> 10 in r
  False
  >>> list(r)
  [1, 2, 3, 4, 5, 6, 7, 8, 9]

If you want numeric-range checks, Python provides the lovely double-comparison syntax:

  >>> x = 5
  >>> 2 < x < 10
  True
  >>> x = 5.5
  >>> 2 < x < 10
  True
  >>> s = "5"
  >>> 2 < s < 10
  Traceback?
  >>> 2 < int(s) < 10
  True

Hopefully this gives you the hints that you need to troubleshoot.

-tkc







From 2QdxY4RzWzUUiLuE at potatochowder.com  Mon Dec 14 17:37:13 2020
From: 2QdxY4RzWzUUiLuE at potatochowder.com (2QdxY4RzWzUUiLuE at potatochowder.com)
Date: Mon, 14 Dec 2020 16:37:13 -0600
Subject: To check if number is in range(x,y)
In-Reply-To: <BN8PR14MB28515D34591ADF2A5EBCC62EF5C70@BN8PR14MB2851.namprd14.prod.outlook.com>
References: <slrnrt9neo.40a.Bischoop@vimart.net>
 <20201212105100.68a7568e@bigbox.attlocal.net>
 <BN8PR14MB28515D34591ADF2A5EBCC62EF5C70@BN8PR14MB2851.namprd14.prod.outlook.com>
Message-ID: <X9fpGRux9XC0Whzr@scrozzle>

On 2020-12-14 at 21:21:43 +0000,
"Schachner, Joseph" <Joseph.Schachner at Teledyne.com> wrote:

> >>> r = range(10)
> So r is a list containing 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

In a number of ways, r behaves as if it were that list, but r is
definitely not that list:

    >>> r = range(10)
    >>> type(r)
    <class 'range'>
    >>> l = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
    >>> type(l)
    <class 'list'>
    >>> r == l
    False

> You have just discovered that Python, although it is dynamically
> typed, is STRICTLY typed.  Another way to say this: you have
> discovered that Python isn't the same as BASIC ...

Citation needed?  I can't speak for every version of BASIC ever, but the
ones I used had separate namespaces for numeric variables and string
variables:  A was a number, A$ was a string, and never the twain shall
meet.  That's strict typing.

From drsalists at gmail.com  Mon Dec 14 18:07:33 2020
From: drsalists at gmail.com (Dan Stromberg)
Date: Mon, 14 Dec 2020 15:07:33 -0800
Subject: To check if number is in range(x,y)
In-Reply-To: <BN8PR14MB28515D34591ADF2A5EBCC62EF5C70@BN8PR14MB2851.namprd14.prod.outlook.com>
References: <slrnrt9neo.40a.Bischoop@vimart.net>
 <20201212105100.68a7568e@bigbox.attlocal.net>
 <BN8PR14MB28515D34591ADF2A5EBCC62EF5C70@BN8PR14MB2851.namprd14.prod.outlook.com>
Message-ID: <CAGGBd_qd-YQg6WzLJq6Yvo5y4xfTCUSHHt_kzFnFybR3yg526A@mail.gmail.com>

On Mon, Dec 14, 2020 at 1:23 PM Schachner, Joseph <
Joseph.Schachner at teledyne.com> wrote:

> >>> r = range(10)
> So r is a list containing 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
>
To get a list of consecutive int's, you can use, for EG:
r = list(range(10))

From drsalists at gmail.com  Mon Dec 14 18:37:27 2020
From: drsalists at gmail.com (Dan Stromberg)
Date: Mon, 14 Dec 2020 15:37:27 -0800
Subject: To check if number is in range(x,y)
In-Reply-To: <CAGGBd_qd-YQg6WzLJq6Yvo5y4xfTCUSHHt_kzFnFybR3yg526A@mail.gmail.com>
References: <slrnrt9neo.40a.Bischoop@vimart.net>
 <20201212105100.68a7568e@bigbox.attlocal.net>
 <BN8PR14MB28515D34591ADF2A5EBCC62EF5C70@BN8PR14MB2851.namprd14.prod.outlook.com>
 <CAGGBd_qd-YQg6WzLJq6Yvo5y4xfTCUSHHt_kzFnFybR3yg526A@mail.gmail.com>
Message-ID: <CAGGBd_ov0MyVgz13JtTGO6Mq9avJg6x2hS04iOHRo+AUpkTXog@mail.gmail.com>

On Mon, Dec 14, 2020 at 3:07 PM Dan Stromberg <drsalists at gmail.com> wrote:

>
> On Mon, Dec 14, 2020 at 1:23 PM Schachner, Joseph <
> Joseph.Schachner at teledyne.com> wrote:
>
>> >>> r = range(10)
>> So r is a list containing 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
>>
> To get a list of consecutive int's, you can use, for EG:
> r = list(range(10))
>

Oh, and range() returning a (lazy) range is a new thing.  In Python 2.x,
range returned a list and you had to use xrange to get laziness.

From python.list at tim.thechases.com  Mon Dec 14 20:50:56 2020
From: python.list at tim.thechases.com (Tim Chase)
Date: Mon, 14 Dec 2020 19:50:56 -0600
Subject: To check if number is in range(x,y)
In-Reply-To: <BN8PR14MB28515D34591ADF2A5EBCC62EF5C70@BN8PR14MB2851.namprd14.prod.outlook.com>
References: <slrnrt9neo.40a.Bischoop@vimart.net>
 <20201212105100.68a7568e@bigbox.attlocal.net>
 <BN8PR14MB28515D34591ADF2A5EBCC62EF5C70@BN8PR14MB2851.namprd14.prod.outlook.com>
Message-ID: <20201214195056.5b3a198f@bigbox.attlocal.net>

On 2020-12-14 21:21, Schachner, Joseph wrote:
> >>> r = range(10)  
> So r is a list containing 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

In Python 3.x, r is *not* a list.  It is a custom object/class.

>   >>> 2 in r  
>   True
> As expected.

I'm not sure what your replies are suggesting here.  I demonstrated
the OP's edge-cases, especially cases that one might experience coming
from other languages.

>   >>> r = range(1, 10, 2)
>   >>> 2 in r  
>   False
>   >>> list(r)  
>   [1, 3, 5, 7, 9]
> Well, yes, because you started the range at 1.  Start at 0 and
> you'd get 0, 2, 4, 6, 8.

Had I done this, for pedagogical value I would have checked for 3
then:

  >>> r = range(0, 10, 2)
  >>> 3 in r
  False

The goal was to demonstrate that the resulting range object, when
given a step-size of something than the default 1, will have holes in
it, and as such, testing for membership in one of those holes would
fail.  Showing successful membership wouldn't add any value.

> "It also doesn't automatically convert from the string inputs
> you're getting from the input() function:
> 
>   >>> s = "5"
>   >>> s in r  
>   False
>   >>> int(s) in r  
>   True"
> You have just discovered that Python, although it is dynamically
> typed, is STRICTLY typed. 

No, not just now discovered something I've long known.  The goal was
to provide an example for the OP of this exact case since their
original code attempted to use the string returned from input() and
used it as-is (without converting to int) for this exact sort of
comparison.

> Another way to say this: you have discovered that Python isn't the
> same as BASIC.

Additionally, (many? all? some?) BASICs have similarly strict typing.
For example, reaching for the BASIC that I used in the 80s:

  ] S$ = "HELLO"
  ] I = 42
  ] PRINT S$ + I
  ?TYPE MISMATCH ERROR

> "Additionally, note that the endpoint of the range is exclusive so
>   >>> r = range(1, 10)
>   >>> 10 in r  
>   False"
> 
> I don't have to note that

My comment was directed at the OP.  Unless you are Bischoop, that's
not you.

> Now suppose that the end integer was not excluded. Each range call
> would produce 11 integers. 

The goal was to show the OP that while some languages (such as the
aforementioned BASIC) have *inclusive* ranges:
  
  ] FOR I = 1 to 3 : PRINT I : NEXT
  1
  2
  3

Python's ranges are exclusive.  Because a language could have either,
the example demonstrated Python's choice.

> I recommend you read Python 101 and when you've done that, read
> Python 201.   I think they are very good "learn Python" books. If
> you're surprised that the end point is not included in range, you
> need to read Python 101.

Your condescending replies bark up the wrong tree.

-tkc







From nospam at please.ty  Tue Dec 15 04:41:24 2020
From: nospam at please.ty (jak)
Date: Tue, 15 Dec 2020 10:41:24 +0100
Subject: Returning from a multiple stacked call at once
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
 <24532.64465.213850.33597@ixdm.fritz.box>
 <mailman.374.1607795388.7193.python-list@python.org>
Message-ID: <rra0c3$j1i$1@gioia.aioe.org>

Il 12/12/2020 18:20, Dieter Maurer ha scritto:
> ast wrote at 2020-12-12 07:39 +0100:
>> In case a function recursively calls itself many times,
>> is there a way to return a data immediately without
>> unstacking all functions ?
> 
> Python does not have "long jump"s (out of many functions, many loop
> incarnations).
> In some cases, you can use exceptions to emulate "long jump"s.
> 

I don't know what you mean by 'emulating' because using the exception 
handler you simply defer unstacking to it. The real problem is that if 
you write a function that ends by calling itself and does not take 
advantage of the branch of code following the recursive call, then it is 
a wrong way to use a recursive function which should be replaced with a 
simple one containing a loop where you can insert a break statement 
wherever you like. IMHO

Greetings.

From nospam at please.ty  Tue Dec 15 05:52:00 2020
From: nospam at please.ty (jak)
Date: Tue, 15 Dec 2020 11:52:00 +0100
Subject: Returning from a multiple stacked call at once
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
 <24532.64465.213850.33597@ixdm.fritz.box>
 <mailman.374.1607795388.7193.python-list@python.org>
 <rra0c3$j1i$1@gioia.aioe.org>
Message-ID: <rra4ge$j92$1@gioia.aioe.org>

Il 15/12/2020 10:41, jak ha scritto:
> Il 12/12/2020 18:20, Dieter Maurer ha scritto:
>> ast wrote at 2020-12-12 07:39 +0100:
>>> In case a function recursively calls itself many times,
>>> is there a way to return a data immediately without
>>> unstacking all functions ?
>>
>> Python does not have "long jump"s (out of many functions, many loop
>> incarnations).
>> In some cases, you can use exceptions to emulate "long jump"s.
>>
> 
> I don't know what you mean by 'emulating' because using the exception 
> handler you simply defer unstacking to it. The real problem is that if 
> you write a function that ends by calling itself and does not take 
> advantage of the branch of code following the recursive call, then it is 
> a wrong way to use a recursive function which should be replaced with a 
> simple one containing a loop where you can insert a break statement 
> wherever you like. IMHO
> 
> Greetings.


this could be a way to emulate a long_jump:

def f(i):
     if i < 10:
         i += 1
         yield from f(i)
     else:
         yield i

i = 0
retult = 0
for n in f(i):
     result = n
     break
print(result)


From rosuav at gmail.com  Tue Dec 15 06:25:58 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 15 Dec 2020 22:25:58 +1100
Subject: Returning from a multiple stacked call at once
In-Reply-To: <rra4ge$j92$1@gioia.aioe.org>
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
 <24532.64465.213850.33597@ixdm.fritz.box>
 <mailman.374.1607795388.7193.python-list@python.org>
 <rra0c3$j1i$1@gioia.aioe.org> <rra4ge$j92$1@gioia.aioe.org>
Message-ID: <CAPTjJmoaQ9cEhS-mZJiS2fKHPBaiGKmKnWKFgt5-0dJjWy2nWg@mail.gmail.com>

On Tue, Dec 15, 2020 at 9:56 PM jak <nospam at please.ty> wrote:
>
> this could be a way to emulate a long_jump:
>
> def f(i):
>      if i < 10:
>          i += 1
>          yield from f(i)
>      else:
>          yield i
>
> i = 0
> retult = 0
> for n in f(i):
>      result = n
>      break
> print(result)
>

Note that this requires just as much cooperation as this version does:

def f(i):
    if i < 10:
        return f(i + 1)
    return i

result = f(0)

The only difference is that "yield from" sorta kinda gives you a
"maybe return", but you're not actually using that in your example, so
it doesn't showcase that. But let's say you're searching a complex
data structure for something:

def find(obj, pred):
    if pred(obj): yield obj
    if isinstance(obj, list):
        for elem in obj: yield from find(elem, pred)
    if isinstance(obj, dict):
        for elem in obj.values(): yield from find(elem, pred)

Taking the first matching element could be done without worrying too
much about whether any subsequent elements would match. I wouldn't
really call this a "long jump", though; this is a lazy filter that can
be efficiently used to locate the first few results without
calculating them all.

ChrisA

From nospam at please.ty  Tue Dec 15 06:31:21 2020
From: nospam at please.ty (jak)
Date: Tue, 15 Dec 2020 12:31:21 +0100
Subject: Returning from a multiple stacked call at once
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
Message-ID: <rra6q8$1se4$1@gioia.aioe.org>

Il 12/12/2020 07:39, ast ha scritto:
> Hello
> 
> In case a function recursively calls itself many times,
> is there a way to return a data immediately without
> unstacking all functions ?
> 

try this way:

def path_finder(graph, start, end, path=[]):
     if start in path:
         yield None
     if start == end:
         yield path + [start]  # Found !
     if start not in graph:
         yield None

     path = path + [start]

     for node in graph[start]:
         found_path = yield from path_finder(graph, node, end, path)
         if found_path:
             yield found_path
     yield None


graph = {'A': ['B', 'C'],
          'B': ['C', 'D'],
          'C': ['D'],
          'D': ['C'],
          'E': ['F'],
          'F': ['C']}
result = []
for r in path_finder(graph, 'A', 'D'):
     result = r
     break
print(result)

From nospam at please.ty  Tue Dec 15 06:39:29 2020
From: nospam at please.ty (jak)
Date: Tue, 15 Dec 2020 12:39:29 +0100
Subject: Returning from a multiple stacked call at once
References: <5fd465b5$0$8956$426a74cc@news.free.fr>
 <24532.64465.213850.33597@ixdm.fritz.box>
 <mailman.374.1607795388.7193.python-list@python.org>
 <rra0c3$j1i$1@gioia.aioe.org> <rra4ge$j92$1@gioia.aioe.org>
 <CAPTjJmoaQ9cEhS-mZJiS2fKHPBaiGKmKnWKFgt5-0dJjWy2nWg@mail.gmail.com>
 <mailman.391.1608031571.7193.python-list@python.org>
Message-ID: <rra79f$44g$1@gioia.aioe.org>

Il 15/12/2020 12:25, Chris Angelico ha scritto:
> On Tue, Dec 15, 2020 at 9:56 PM jak <nospam at please.ty> wrote:
>>
>> this could be a way to emulate a long_jump:
>>
>> def f(i):
>>       if i < 10:
>>           i += 1
>>           yield from f(i)
>>       else:
>>           yield i
>>
>> i = 0
>> retult = 0
>> for n in f(i):
>>       result = n
>>       break
>> print(result)
>>
> 
> Note that this requires just as much cooperation as this version does:
> 
> def f(i):
>      if i < 10:
>          return f(i + 1)
>      return i
> 
> result = f(0)
> 
> The only difference is that "yield from" sorta kinda gives you a
> "maybe return", but you're not actually using that in your example, so
> it doesn't showcase that. But let's say you're searching a complex
> data structure for something:
> 
> def find(obj, pred):
>      if pred(obj): yield obj
>      if isinstance(obj, list):
>          for elem in obj: yield from find(elem, pred)
>      if isinstance(obj, dict):
>          for elem in obj.values(): yield from find(elem, pred)
> 
> Taking the first matching element could be done without worrying too
> much about whether any subsequent elements would match. I wouldn't
> really call this a "long jump", though; this is a lazy filter that can
> be efficiently used to locate the first few results without
> calculating them all.
> 
> ChrisA
> 

You are right. In fact I used the word 'emulate' to mean that this is 
what (IMO) comes closest to a long jump.

Cheers.

From phd at phdru.name  Tue Dec 15 09:22:43 2020
From: phd at phdru.name (Oleg Broytman)
Date: Tue, 15 Dec 2020 15:22:43 +0100
Subject: SQLObject 3.9.0
Message-ID: <20201215142243.GA30282@phdru.name>

Hello!

I'm pleased to announce version 3.9.0, the first release
of branch 3.9 of SQLObject.


What's new in SQLObject
=======================

Contributors for this release are:

+ Michael S. Root, Ameya Bapat - ``JSONCol``;

+ Jerry Nance - reported a bug with ``DateTime`` from ``Zope``.

Features
--------

* Add ``JSONCol``: a universal json column that converts simple Python objects
  (None, bool, int, float, long, dict, list, str/unicode to/from JSON using
  json.dumps/loads. A subclass of StringCol. Requires ``VARCHAR``/``TEXT``
  columns at backends, doesn't work with ``JSON`` columns.

* Extend/fix support for ``DateTime`` from ``Zope``.

* Drop support for very old version of ``mxDateTime``
  without ``mx.`` namespace.

Drivers
-------

* Support `mariadb <https://pypi.org/project/mariadb/>`_.

CI
--

* Run tests with Python 3.9 at Travis and AppVeyor.

For a more complete list, please see the news:
http://sqlobject.org/News.html


What is SQLObject
=================

SQLObject is an object-relational mapper.  Your database tables are described
as classes, and rows are instances of those classes.  SQLObject is meant to be
easy to use and quick to get started with.

It currently supports MySQL, PostgreSQL and SQLite; connections to other
backends - Firebird, Sybase, MSSQL and MaxDB (also known as SAPDB) - are
lesser debugged).

Python 2.7 or 3.4+ is required.


Where is SQLObject
==================

Site:
http://sqlobject.org

Development:
http://sqlobject.org/devel/

Mailing list:
https://lists.sourceforge.net/mailman/listinfo/sqlobject-discuss

Download:
https://pypi.org/project/SQLObject/3.9.0

News and changes:
http://sqlobject.org/News.html

StackOverflow:
https://stackoverflow.com/questions/tagged/sqlobject


Example
=======

Create a simple class that wraps a table::

  >>> from sqlobject import *
  >>>
  >>> sqlhub.processConnection = connectionForURI('sqlite:/:memory:')
  >>>
  >>> class Person(SQLObject):
  ...     fname = StringCol()
  ...     mi = StringCol(length=1, default=None)
  ...     lname = StringCol()
  ...
  >>> Person.createTable()

Use the object::

  >>> p = Person(fname="John", lname="Doe")
  >>> p
  <Person 1 fname='John' mi=None lname='Doe'>
  >>> p.fname
  'John'
  >>> p.mi = 'Q'
  >>> p2 = Person.get(1)
  >>> p2
  <Person 1 fname='John' mi='Q' lname='Doe'>
  >>> p is p2
  True

Queries::

  >>> p3 = Person.selectBy(lname="Doe")[0]
  >>> p3
  <Person 1 fname='John' mi='Q' lname='Doe'>
  >>> pc = Person.select(Person.q.lname=="Doe").count()
  >>> pc
  1

Oleg.
-- 
    Oleg Broytman            https://phdru.name/            phd at phdru.name
           Programmers don't die, they just GOSUB without RETURN.

From lists at mostrom.pp.se  Tue Dec 15 10:04:55 2020
From: lists at mostrom.pp.se (Jan Erik =?utf-8?q?Mostr=C3=B6m?=)
Date: Tue, 15 Dec 2020 16:04:55 +0100
Subject: Library for text substitutions with calculations?
Message-ID: <D6C434DD-E088-4140-953D-45CEEE570CF0@mostrom.pp.se>

I want to do some text substitutions but a bit more advanced than what 
string.Template class can do. I addition to plain text substitution I 
would like to be able to do some calculations:

$value+1 - If value is 16 this would insert 17 in the text. I would also 
like to subtract.

$value+1w - In this case value would be a date, this would add a week to 
that date, similar for year, month, hours. Also subtract.

The exact syntax isn't important.

In other words I would like to define

example1 = 12
example2 = 2020-12-15

and then some text:

Hello world $example1+10 and a date $example+1w

would result in

Hello world 22 and a date 2020-12-22

Is there some library that can do something like this?

I probably searching using the wrong keywords because I can't find 
anything.

= jem

From 2QdxY4RzWzUUiLuE at potatochowder.com  Tue Dec 15 10:41:56 2020
From: 2QdxY4RzWzUUiLuE at potatochowder.com (2QdxY4RzWzUUiLuE at potatochowder.com)
Date: Tue, 15 Dec 2020 09:41:56 -0600
Subject: Library for text substitutions with calculations?
In-Reply-To: <D6C434DD-E088-4140-953D-45CEEE570CF0@mostrom.pp.se>
References: <D6C434DD-E088-4140-953D-45CEEE570CF0@mostrom.pp.se>
Message-ID: <X9jZRIZ43JAL3hca@scrozzle>

On 2020-12-15 at 16:04:55 +0100,
Jan Erik Mostr?m <lists at mostrom.pp.se> wrote:

> I want to do some text substitutions but a bit more advanced than what
> string.Template class can do. I addition to plain text substitution I would
> like to be able to do some calculations:
> 
> $value+1 - If value is 16 this would insert 17 in the text. I would also
> like to subtract.

[...]

A lot of libraries for making web pages can do things like that; a
starting point is <https://wiki.python.org/moin/Templating>.

HTH,
Dan

From rshepard at appl-ecosys.com  Tue Dec 15 10:52:31 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Tue, 15 Dec 2020 07:52:31 -0800 (PST)
Subject: Python3 change logs
Message-ID: <alpine.LNX.2.20.2012150749530.32731@salmo.appl-ecosys.com>

I've upgraded from Python-3.7.x to Python-3.9.x and want to learn about
differences (if any) in tkinter between the two versions.

Looking on the python.org web site I did not find change logs with the
sources or under the other menus I checked. Please point me to any available
logs.

Regards,

Rich

From bgailer at gmail.com  Tue Dec 15 11:25:13 2020
From: bgailer at gmail.com (Bob Gailer)
Date: Tue, 15 Dec 2020 11:25:13 -0500
Subject: Library for text substitutions with calculations?
In-Reply-To: <X9jZRIZ43JAL3hca@scrozzle>
References: <D6C434DD-E088-4140-953D-45CEEE570CF0@mostrom.pp.se>
 <X9jZRIZ43JAL3hca@scrozzle>
Message-ID: <CAP1rxO7YWcrMHGyKL3aZ_oVoa4MVdb+sdVdXZzb=GvbzSX32-Q@mail.gmail.com>

On Tue, Dec 15, 2020, 10:42 AM <2QdxY4RzWzUUiLuE at potatochowder.com> wrote:

> On 2020-12-15 at 16:04:55 +0100,
> Jan Erik Mostr?m <lists at mostrom.pp.se> wrote:
>
> > I want to do some text substitutions but a bit more advanced than what
> > string.Template class can do. I addition to plain text substitution I
> would
> > like to be able to do some calculations:
> >
> > $value+1 - If value is 16 this would insert 17 in the text. I would also
> > like to subtract.
>
> val = 2

print(f'{val+3}')

5

Bob Gailer

From markpolesky at yahoo.com  Tue Dec 15 12:07:16 2020
From: markpolesky at yahoo.com (Mark Polesky)
Date: Tue, 15 Dec 2020 17:07:16 +0000 (UTC)
Subject: dict.get(key, default) evaluates default even if key exists
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
Message-ID: <263519400.745131.1608052036522@mail.yahoo.com>

Hi.

# Running this script....

D = {'a':1}
def get_default():
??? print('Nobody expects this')
??? return 0
print(D.get('a', get_default()))

# ...generates this output:

Nobody expects this
1

###

Since I'm brand new to this community, I thought I'd ask here first... Is this worthy of a bug report?? This behavior is definitely unexpected to me, and I accidentally coded an endless loop in a mutual recursion situation because of it.? Calling dict.get.__doc__ only gives this short sentence: Return the value for key if key is in the dictionary, else default.? Nothing in that docstring suggests that the default value is evaluated even if the key exists, and I can't think of any good reason to do so.

Am I missing something?

Thanks,
Mark

From skip.montanaro at gmail.com  Tue Dec 15 13:35:19 2020
From: skip.montanaro at gmail.com (Skip Montanaro)
Date: Tue, 15 Dec 2020 12:35:19 -0600
Subject: Python3 change logs
In-Reply-To: <alpine.LNX.2.20.2012150749530.32731@salmo.appl-ecosys.com>
References: <alpine.LNX.2.20.2012150749530.32731@salmo.appl-ecosys.com>
Message-ID: <CANc-5UygZkZR852emcjQDjJ2wovY0tjQBmzRYHGarqz3U0=NXQ@mail.gmail.com>

Change logs are kept as part of the source, I believe. Try browsing the
cpython GitHub repo:

https://github.com/python/cpython

Skip

On Tue, Dec 15, 2020, 10:05 AM Rich Shepard <rshepard at appl-ecosys.com>
wrote:

> I've upgraded from Python-3.7.x to Python-3.9.x and want to learn about
> differences (if any) in tkinter between the two versions.
>
> Looking on the python.org web site I did not find change logs with the
> sources or under the other menus I checked. Please point me to any
> available
> logs.
>
> Regards,
>
> Rich
> --
> https://mail.python.org/mailman/listinfo/python-list
>

From skip.montanaro at gmail.com  Tue Dec 15 13:39:36 2020
From: skip.montanaro at gmail.com (Skip Montanaro)
Date: Tue, 15 Dec 2020 12:39:36 -0600
Subject: Python3 change logs
In-Reply-To: <CANc-5UygZkZR852emcjQDjJ2wovY0tjQBmzRYHGarqz3U0=NXQ@mail.gmail.com>
References: <alpine.LNX.2.20.2012150749530.32731@salmo.appl-ecosys.com>
 <CANc-5UygZkZR852emcjQDjJ2wovY0tjQBmzRYHGarqz3U0=NXQ@mail.gmail.com>
Message-ID: <CANc-5UzmVxq5GQp4hK3ATPbtp4Bmb7CCKjG7_dLWWUoqzoZ2hQ@mail.gmail.com>

Also, check www.python.org for "What's New" pages. I believe one is
generated for every release. It will be less detailed than change logs in
GitHub, but more reader friendly.

Skip

From skip.montanaro at gmail.com  Tue Dec 15 13:42:04 2020
From: skip.montanaro at gmail.com (Skip Montanaro)
Date: Tue, 15 Dec 2020 12:42:04 -0600
Subject: Python3 change logs
In-Reply-To: <CANc-5UzmVxq5GQp4hK3ATPbtp4Bmb7CCKjG7_dLWWUoqzoZ2hQ@mail.gmail.com>
References: <alpine.LNX.2.20.2012150749530.32731@salmo.appl-ecosys.com>
 <CANc-5UygZkZR852emcjQDjJ2wovY0tjQBmzRYHGarqz3U0=NXQ@mail.gmail.com>
 <CANc-5UzmVxq5GQp4hK3ATPbtp4Bmb7CCKjG7_dLWWUoqzoZ2hQ@mail.gmail.com>
Message-ID: <CANc-5UxF3dcpxQ8eYCT9__8Xmw2dfsc-ZT=0-hOMky1oHv7ouQ@mail.gmail.com>

Dang... I'm having very incomplete thoughts. Apologies for the multiple
replies when one would have sufficed.

https://docs.python.org/3/whatsnew/3.9.html

Skip

From drsalists at gmail.com  Tue Dec 15 13:52:42 2020
From: drsalists at gmail.com (Dan Stromberg)
Date: Tue, 15 Dec 2020 10:52:42 -0800
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <263519400.745131.1608052036522@mail.yahoo.com>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
Message-ID: <CAGGBd_ows0hnjj9ymVWAEadkNR5JJJruZb=pn4WFjzZzFLRJjg@mail.gmail.com>

On Tue, Dec 15, 2020 at 9:57 AM Mark Polesky via Python-list <
python-list at python.org> wrote:

> Hi.
>
> # Running this script....
>
> D = {'a':1}
> def get_default():
>     print('Nobody expects this')
>     return 0
> print(D.get('a', get_default()))
>
> # ...generates this output:
>
> Nobody expects this
> 1
>
> ###
>
> Since I'm brand new to this community, I thought I'd ask here first... Is
> this worthy of a bug report?  This behavior is definitely unexpected to me,
> and I accidentally coded an endless loop in a mutual recursion situation
> because of it.  Calling dict.get.__doc__ only gives this short sentence:
> Return the value for key if key is in the dictionary, else default.
> Nothing in that docstring suggests that the default value is evaluated even
> if the key exists, and I can't think of any good reason to do so.
>

Python isn't a lazy language.  It's evaluating get_default()
unconditionally, prior to executing the D.get().  I don't think it's a
Python bug.

BTW, I tend to prefer collections.defaultdict over the two argument D.get
or setdefault.

From rosuav at gmail.com  Tue Dec 15 13:57:06 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 16 Dec 2020 05:57:06 +1100
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <263519400.745131.1608052036522@mail.yahoo.com>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
Message-ID: <CAPTjJmoiSjniNjFqv91cn+jUP7tggwxBKua8xz6zLVDUCxeHXA@mail.gmail.com>

On Wed, Dec 16, 2020 at 4:58 AM Mark Polesky via Python-list
<python-list at python.org> wrote:
>
> Hi.
>
> # Running this script....
>
> D = {'a':1}
> def get_default():
>     print('Nobody expects this')
>     return 0
> print(D.get('a', get_default()))
>
> # ...generates this output:
>
> Nobody expects this
> 1
>
> ###
>
> Since I'm brand new to this community, I thought I'd ask here first... Is this worthy of a bug report?  This behavior is definitely unexpected to me, and I accidentally coded an endless loop in a mutual recursion situation because of it.  Calling dict.get.__doc__ only gives this short sentence: Return the value for key if key is in the dictionary, else default.  Nothing in that docstring suggests that the default value is evaluated even if the key exists, and I can't think of any good reason to do so.
>
> Am I missing something?
>

Seems what you want is the __missing__ method. Look into it - I think
it will do what you're expecting here.

ChrisA

From storchaka at gmail.com  Tue Dec 15 13:57:15 2020
From: storchaka at gmail.com (Serhiy Storchaka)
Date: Tue, 15 Dec 2020 20:57:15 +0200
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <263519400.745131.1608052036522@mail.yahoo.com>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
Message-ID: <rrb0ug$88n$1@ciao.gmane.io>

15.12.20 19:07, Mark Polesky via Python-list ????:
> # Running this script....
> 
> D = {'a':1}
> def get_default():
> ??? print('Nobody expects this')
> ??? return 0
> print(D.get('a', get_default()))
> 
> # ...generates this output:
> 
> Nobody expects this
> 1
> 
> ###
> 
> Since I'm brand new to this community, I thought I'd ask here first... Is this worthy of a bug report?? This behavior is definitely unexpected to me, and I accidentally coded an endless loop in a mutual recursion situation because of it.? Calling dict.get.__doc__ only gives this short sentence: Return the value for key if key is in the dictionary, else default.? Nothing in that docstring suggests that the default value is evaluated even if the key exists, and I can't think of any good reason to do so.
> 
> Am I missing something?

You are missed that expressions for function arguments are always
evaluated before passing their values to a function. This is expected
behavior, and I can't remember any programming language in which it's
different.

So dict.get() returns the value of argument default, which is computed
by calling function get_default() before calling dict.get().


From rshepard at appl-ecosys.com  Tue Dec 15 14:17:19 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Tue, 15 Dec 2020 11:17:19 -0800 (PST)
Subject: Python3 change logs
In-Reply-To: <CANc-5UygZkZR852emcjQDjJ2wovY0tjQBmzRYHGarqz3U0=NXQ@mail.gmail.com>
References: <alpine.LNX.2.20.2012150749530.32731@salmo.appl-ecosys.com>
 <CANc-5UygZkZR852emcjQDjJ2wovY0tjQBmzRYHGarqz3U0=NXQ@mail.gmail.com>
Message-ID: <alpine.LNX.2.20.2012151117010.32731@salmo.appl-ecosys.com>

On Tue, 15 Dec 2020, Skip Montanaro wrote:

> Change logs are kept as part of the source, I believe. Try browsing the
> cpython GitHub repo:
> https://github.com/python/cpython

Skip,

Thanks, I will.

Stay well,

Rich

From rshepard at appl-ecosys.com  Tue Dec 15 14:22:41 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Tue, 15 Dec 2020 11:22:41 -0800 (PST)
Subject: Python3 change logs
In-Reply-To: <CANc-5UzmVxq5GQp4hK3ATPbtp4Bmb7CCKjG7_dLWWUoqzoZ2hQ@mail.gmail.com>
References: <alpine.LNX.2.20.2012150749530.32731@salmo.appl-ecosys.com>
 <CANc-5UygZkZR852emcjQDjJ2wovY0tjQBmzRYHGarqz3U0=NXQ@mail.gmail.com>
 <CANc-5UzmVxq5GQp4hK3ATPbtp4Bmb7CCKjG7_dLWWUoqzoZ2hQ@mail.gmail.com>
Message-ID: <alpine.LNX.2.20.2012151118440.32731@salmo.appl-ecosys.com>

On Tue, 15 Dec 2020, Skip Montanaro wrote:

> Also, check www.python.org for "What's New" pages. I believe one is
> generated for every release. It will be less detailed than change logs in
> GitHub, but more reader friendly.

Skip,

I don't find a "What's New" page, but under Download -> All Releases (rather
than Source code) there's a column of Release Notes for each version. I'll
check github, too.

Thanks,

Rich

From rshepard at appl-ecosys.com  Tue Dec 15 14:24:31 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Tue, 15 Dec 2020 11:24:31 -0800 (PST)
Subject: Python3 change logs
In-Reply-To: <CANc-5UxF3dcpxQ8eYCT9__8Xmw2dfsc-ZT=0-hOMky1oHv7ouQ@mail.gmail.com>
References: <alpine.LNX.2.20.2012150749530.32731@salmo.appl-ecosys.com>
 <CANc-5UygZkZR852emcjQDjJ2wovY0tjQBmzRYHGarqz3U0=NXQ@mail.gmail.com>
 <CANc-5UzmVxq5GQp4hK3ATPbtp4Bmb7CCKjG7_dLWWUoqzoZ2hQ@mail.gmail.com>
 <CANc-5UxF3dcpxQ8eYCT9__8Xmw2dfsc-ZT=0-hOMky1oHv7ouQ@mail.gmail.com>
Message-ID: <alpine.LNX.2.20.2012151123360.32731@salmo.appl-ecosys.com>

On Tue, 15 Dec 2020, Skip Montanaro wrote:

> Dang... I'm having very incomplete thoughts. Apologies for the multiple
> replies when one would have sufficed.
> https://docs.python.org/3/whatsnew/3.9.html

Skip,

No apologies needed. That page looks like a reformatted Release Notes.

Thanks again,

Rich

From markpolesky at yahoo.com  Tue Dec 15 15:08:53 2020
From: markpolesky at yahoo.com (Mark Polesky)
Date: Tue, 15 Dec 2020 20:08:53 +0000 (UTC)
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <rrb0ug$88n$1@ciao.gmane.io>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com> <rrb0ug$88n$1@ciao.gmane.io>
Message-ID: <1823740026.830499.1608062933098@mail.yahoo.com>

I see. Perhaps counterintuitive, but implemented consistently. Add it to the list of gotchas, I guess.

By the way... four helpful responses in under an hour, very impressive. Nice community here. Thanks to all who answered.

Mark






On Tuesday, December 15, 2020, 11:05:10 AM PST, Serhiy Storchaka <storchaka at gmail.com> wrote: 





15.12.20 19:07, Mark Polesky via Python-list ????:

> # Running this script....
> 
> D = {'a':1}
> def get_default():
> ??? print('Nobody expects this')
> ??? return 0
> print(D.get('a', get_default()))
> 
> # ...generates this output:
> 
> Nobody expects this
> 1
> 
> ###
> 
> Since I'm brand new to this community, I thought I'd ask here first... Is this worthy of a bug report?? This behavior is definitely unexpected to me, and I accidentally coded an endless loop in a mutual recursion situation because of it.? Calling dict.get.__doc__ only gives this short sentence: Return the value for key if key is in the dictionary, else default.? Nothing in that docstring suggests that the default value is evaluated even if the key exists, and I can't think of any good reason to do so.
> 
> Am I missing something?


You are missed that expressions for function arguments are always
evaluated before passing their values to a function. This is expected
behavior, and I can't remember any programming language in which it's
different.

So dict.get() returns the value of argument default, which is computed
by calling function get_default() before calling dict.get().

-- 
https://mail.python.org/mailman/listinfo/python-list


From grant.b.edwards at gmail.com  Tue Dec 15 15:26:23 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Tue, 15 Dec 2020 20:26:23 -0000 (UTC)
Subject: dict.get(key, default) evaluates default even if key exists
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <rrb0ug$88n$1@ciao.gmane.io>
 <1823740026.830499.1608062933098@mail.yahoo.com>
Message-ID: <rrb65f$129h$1@ciao.gmane.io>

On 2020-12-15, Mark Polesky via Python-list <python-list at python.org> wrote:

> I see. Perhaps counterintuitive,

I guess that depends on what programming language you normally think
in. Python's handling of function parameters is exactly what I
expected, because all of the previous languages I used did the same
thing.

Purely out of curiosity, what language had you been using that behaved
otherwise?


From ethan at stoneleaf.us  Tue Dec 15 16:07:25 2020
From: ethan at stoneleaf.us (Ethan Furman)
Date: Tue, 15 Dec 2020 13:07:25 -0800
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <263519400.745131.1608052036522@mail.yahoo.com>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
Message-ID: <3f9bf105-1909-3b3a-4823-eaa450a1a2ec@stoneleaf.us>

On 12/15/20 9:07 AM, Mark Polesky via Python-list wrote:

 > D = {'a':1}
 >
 > def get_default():
 >      print('Nobody expects this')
 >      return 0
 >
 > print(D.get('a', get_default()))

Python has short-circuiting logical operations, so one way to get the behavior you're looking for is:

     D.get('a') or get_default()

--
~Ethan~

From drsalists at gmail.com  Tue Dec 15 16:10:42 2020
From: drsalists at gmail.com (Dan Stromberg)
Date: Tue, 15 Dec 2020 13:10:42 -0800
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <rrb0ug$88n$1@ciao.gmane.io>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com> <rrb0ug$88n$1@ciao.gmane.io>
Message-ID: <CAGGBd_ptgJZ+Lz4CSK48A7EHVkna4MRQn=t5+xgGny8d-q9Srg@mail.gmail.com>

On Tue, Dec 15, 2020 at 11:05 AM Serhiy Storchaka <storchaka at gmail.com>
wrote:

> 15.12.20 19:07, Mark Polesky via Python-list ????:
> > # Running this script....
> >
> > D = {'a':1}
> > def get_default():
> >     print('Nobody expects this')
> >     return 0
> > print(D.get('a', get_default()))
> >
> > # ...generates this output:
> >
> > Nobody expects this
> > 1
> >
> > ###
> >
> > Since I'm brand new to this community, I thought I'd ask here first...
> Is this worthy of a bug report?  This behavior is definitely unexpected to
> me, and I accidentally coded an endless loop in a mutual recursion
> situation because of it.  Calling dict.get.__doc__ only gives this short
> sentence: Return the value for key if key is in the dictionary, else
> default.  Nothing in that docstring suggests that the default value is
> evaluated even if the key exists, and I can't think of any good reason to
> do so.
> >
> > Am I missing something?
>
> You are missed that expressions for function arguments are always
> evaluated before passing their values to a function. This is expected
> behavior, and I can't remember any programming language in which it's
> different.
>
I think Haskell might be different. It's a lazy language. So its '&&' and
'||' operators aren't specialcased by the language implementation to be
short-circuit - everything is just lazy naturally.  It's a neat idea, but
it's kind of hard to reason about its performance characteristics.  Python
has laziness in its 'and' and 'or', as well as in its generators - this
gives laziness where you tend to need it the most, without Python's
performance becoming hard to reason about (modulo the garbage collector).

One of the coolest things about Haskell is if you write a sort function in
it, then you can get a "give me the n lowest values" function for free.
That's lazy.

From PythonList at DancesWithMice.info  Tue Dec 15 18:01:01 2020
From: PythonList at DancesWithMice.info (dn)
Date: Wed, 16 Dec 2020 12:01:01 +1300
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <263519400.745131.1608052036522@mail.yahoo.com>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
Message-ID: <3dd7380c-8998-c42f-52d1-192787314366@DancesWithMice.info>

 > On Tue, Dec 15, 2020 at 9:57 AM Mark Polesky via Python-list <
 > python-list at python.org> wrote:
 >
 >> Hi.
 >>
 >> # Running this script....
 >>
 >> D = {'a':1}
 >> def get_default():
 >>      print('Nobody expects this')
 >>      return 0
 >> print(D.get('a', get_default()))
 >>
 >> # ...generates this output:
 >>
 >> Nobody expects this
 >> 1
 >>
 >> ###
 >>
 >> Since I'm brand new to this community, I thought I'd ask here 
first... Is
 >> this worthy of a bug report?  This behavior is definitely unexpected 
to me,
 >> and I accidentally coded an endless loop in a mutual recursion situation
 >> because of it.  Calling dict.get.__doc__ only gives this short sentence:
 >> Return the value for key if key is in the dictionary, else default.
 >> Nothing in that docstring suggests that the default value is 
evaluated even
 >> if the key exists, and I can't think of any good reason to do so.


Hey this is fun! A quick search reveals that I've (mea culpa) always 
thought of dict.get() as providing a default *value* and not used a 
function in there to provide said value.

That said, the function's name says it all: get_default(). Is it 
'getting' a default value? No, it's (also) reporting-back. Thus a 
"side-effect". Undesirable, as you say.

Were it appropriate to report that a default value was necessary, maybe 
something like:

     try:
         print( d[ 'a' ] )
     except KeyError:
         print( "Nobody expects this" )
         d[ 'a' ] = 0
-- 
Regards =dn

From PythonList at DancesWithMice.info  Tue Dec 15 18:02:14 2020
From: PythonList at DancesWithMice.info (dn)
Date: Wed, 16 Dec 2020 12:02:14 +1300
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <CAGGBd_ows0hnjj9ymVWAEadkNR5JJJruZb=pn4WFjzZzFLRJjg@mail.gmail.com>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <CAGGBd_ows0hnjj9ymVWAEadkNR5JJJruZb=pn4WFjzZzFLRJjg@mail.gmail.com>
Message-ID: <06f87dd0-4618-b7ed-45a5-e55fad2b2d5a@DancesWithMice.info>

On 16/12/2020 07:52, Dan Stromberg wrote:
...> BTW, I tend to prefer collections.defaultdict over the two argument 
D.get
> or setdefault.


Contrarily, dict.get() seems 'better', unless (a) the dict's values are 
all to be initialised to the same value, eg all None, int 0, or empty 
list []; or (b) my fingers will be tired by the number of dict.get() 
calls to be typed.

This thought partly because it may be some 'distance' between the 
definition of the 'dict' as a defaultdict cf the built-in 'original', 
and therefore a simple boy (like me) finds it easy to forget or 'lose 
track'.

Also, because it is unusual to come-across a default-factory which 
initialises values to the defaultdict other than uniformly.

Have you seen any application of defaultdict with some more-complex and 
cleverly-designed default-factory function?

Other than personal-preference (which should be respected), and a 
uniform default-value, what is the rationale for defaultdict over 
dict.get()?
-- 
Regards =dn

From rosuav at gmail.com  Tue Dec 15 18:10:36 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 16 Dec 2020 10:10:36 +1100
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <06f87dd0-4618-b7ed-45a5-e55fad2b2d5a@DancesWithMice.info>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <CAGGBd_ows0hnjj9ymVWAEadkNR5JJJruZb=pn4WFjzZzFLRJjg@mail.gmail.com>
 <06f87dd0-4618-b7ed-45a5-e55fad2b2d5a@DancesWithMice.info>
Message-ID: <CAPTjJmrJM4AK77Rpcw35CD14yofsNusWaHbiTUQVXMooJ_+Lgg@mail.gmail.com>

On Wed, Dec 16, 2020 at 10:03 AM dn via Python-list
<python-list at python.org> wrote:
>
> On 16/12/2020 07:52, Dan Stromberg wrote:
> ...> BTW, I tend to prefer collections.defaultdict over the two argument
> D.get
> > or setdefault.
>
>
> Contrarily, dict.get() seems 'better', unless (a) the dict's values are
> all to be initialised to the same value, eg all None, int 0, or empty
> list []; or (b) my fingers will be tired by the number of dict.get()
> calls to be typed.
>
> This thought partly because it may be some 'distance' between the
> definition of the 'dict' as a defaultdict cf the built-in 'original',
> and therefore a simple boy (like me) finds it easy to forget or 'lose
> track'.
>
> Also, because it is unusual to come-across a default-factory which
> initialises values to the defaultdict other than uniformly.
>
> Have you seen any application of defaultdict with some more-complex and
> cleverly-designed default-factory function?
>
> Other than personal-preference (which should be respected), and a
> uniform default-value, what is the rationale for defaultdict over
> dict.get()?

It depends on use-case. Using dict.get() is appropriate when you want
to know if something's there without prepopulating it; but if your
entire purpose is to then stash something into the dict, and you'll
ALWAYS be following the same pattern, then it's often more convenient
to use __missing__. And if your __missing__ method is, as it commonly
will be, constructing a brand new object, then it's easiest to use
defaultdict. But a defaultdict for integers might be better written as
a Counter instead. There are a lot of similar options, and you take
whatever's easiest for this particular job.

One VERY common use-case is gathering things together into lists based
on some sort of lookup key. This one is perfect for defaultdict:

messages = defaultdict(list)
for msg in get_messages():
    messages[msg["author"]].append(msg)

That'll quickly and easily group the messages by their authors. The
first time an author is found, a new list is created, and then you
append them all.

(In digging for examples, I actually found a place where I'd used
defaultdict(collections.Counter) to create a nested structure very
easily. Worked out well. Pretty unusual thing to want though!)

ChrisA

From tjreedy at udel.edu  Tue Dec 15 21:47:13 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 15 Dec 2020 21:47:13 -0500
Subject: Library for text substitutions with calculations?
In-Reply-To: <CAP1rxO7YWcrMHGyKL3aZ_oVoa4MVdb+sdVdXZzb=GvbzSX32-Q@mail.gmail.com>
References: <D6C434DD-E088-4140-953D-45CEEE570CF0@mostrom.pp.se>
 <X9jZRIZ43JAL3hca@scrozzle>
 <CAP1rxO7YWcrMHGyKL3aZ_oVoa4MVdb+sdVdXZzb=GvbzSX32-Q@mail.gmail.com>
Message-ID: <rrbsfi$2hn$1@ciao.gmane.io>

On 12/15/2020 11:25 AM, Bob Gailer wrote:
> On Tue, Dec 15, 2020, 10:42 AM <2QdxY4RzWzUUiLuE at potatochowder.com> wrote:
> 
>> On 2020-12-15 at 16:04:55 +0100,
>> Jan Erik Mostr?m <lists at mostrom.pp.se> wrote:
>>
>>> I want to do some text substitutions but a bit more advanced than what
>>> string.Template class can do. I addition to plain text substitution I
>> would
>>> like to be able to do some calculations:
>>>
>>> $value+1 - If value is 16 this would insert 17 in the text. I would also
>>> like to subtract.
>>
>> val = 2
> 
> print(f'{val+3}')
> 
> 5

For more, see 
https://docs.python.org/3/reference/lexical_analysis.html#f-strings


-- 
Terry Jan Reedy



From tjreedy at udel.edu  Tue Dec 15 21:52:07 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 15 Dec 2020 21:52:07 -0500
Subject: Python3 change logs
In-Reply-To: <CANc-5UxF3dcpxQ8eYCT9__8Xmw2dfsc-ZT=0-hOMky1oHv7ouQ@mail.gmail.com>
References: <alpine.LNX.2.20.2012150749530.32731@salmo.appl-ecosys.com>
 <CANc-5UygZkZR852emcjQDjJ2wovY0tjQBmzRYHGarqz3U0=NXQ@mail.gmail.com>
 <CANc-5UzmVxq5GQp4hK3ATPbtp4Bmb7CCKjG7_dLWWUoqzoZ2hQ@mail.gmail.com>
 <CANc-5UxF3dcpxQ8eYCT9__8Xmw2dfsc-ZT=0-hOMky1oHv7ouQ@mail.gmail.com>
Message-ID: <rrbsoo$13fn$1@ciao.gmane.io>

On 12/15/2020 1:42 PM, Skip Montanaro wrote:
> Dang... I'm having very incomplete thoughts. Apologies for the multiple
> replies when one would have sufficed.
> 
> https://docs.python.org/3/whatsnew/3.9.html

In particular, for latest release (now 3.9) you would want tkinter in
https://docs.python.org/3/whatsnew/3.9.html#improved-modules
but nothing there.  However,
https://docs.python.org/3.8/whatsnew/3.8.html#tkinter

-- 
Terry Jan Reedy


From 2QdxY4RzWzUUiLuE at potatochowder.com  Tue Dec 15 22:23:59 2020
From: 2QdxY4RzWzUUiLuE at potatochowder.com (2QdxY4RzWzUUiLuE at potatochowder.com)
Date: Tue, 15 Dec 2020 21:23:59 -0600
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <3dd7380c-8998-c42f-52d1-192787314366@DancesWithMice.info>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <3dd7380c-8998-c42f-52d1-192787314366@DancesWithMice.info>
Message-ID: <X9l9zz0nuakUXiEE@scrozzle>

On 2020-12-16 at 12:01:01 +1300,
dn via Python-list <python-list at python.org> wrote:

> > On Tue, Dec 15, 2020 at 9:57 AM Mark Polesky via Python-list <
> > python-list at python.org> wrote:
> >
> >> Hi.
> >>
> >> # Running this script....
> >>
> >> D = {'a':1}
> >> def get_default():
> >>      print('Nobody expects this')
> >>      return 0
> >> print(D.get('a', get_default()))
> >>
> >> # ...generates this output:
> >>
> >> Nobody expects this
> >> 1
> >>
> >> ###
> >>
> >> Since I'm brand new to this community, I thought I'd ask here first... Is
> >> this worthy of a bug report?  This behavior is definitely unexpected to
> me,
> >> and I accidentally coded an endless loop in a mutual recursion situation
> >> because of it.  Calling dict.get.__doc__ only gives this short sentence:
> >> Return the value for key if key is in the dictionary, else default.
> >> Nothing in that docstring suggests that the default value is evaluated
> even
> >> if the key exists, and I can't think of any good reason to do so.
> 
> 
> Hey this is fun! A quick search reveals that I've (mea culpa) always thought
> of dict.get() as providing a default *value* and not used a function in
> there to provide said value.
> 
> That said, the function's name says it all: get_default(). Is it 'getting' a
> default value? No, it's (also) reporting-back. Thus a "side-effect".
> Undesirable, as you say.
> 
> Were it appropriate to report that a default value was necessary, maybe
> something like:
> 
>     try:
>         print( d[ 'a' ] )
>     except KeyError:
>         print( "Nobody expects this" )
>         d[ 'a' ] = 0

Be careful:  that mutates d in the except clause, whereas calling
d.get('a', 0) doesn't, which may or may not be okay.

From mruffalo at cs.cmu.edu  Tue Dec 15 23:23:51 2020
From: mruffalo at cs.cmu.edu (Matt Ruffalo)
Date: Tue, 15 Dec 2020 23:23:51 -0500
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <rrb65f$129h$1@ciao.gmane.io>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com> <rrb0ug$88n$1@ciao.gmane.io>
 <1823740026.830499.1608062933098@mail.yahoo.com>
 <rrb65f$129h$1@ciao.gmane.io>
Message-ID: <08a7c04b-e8c0-a2a4-807e-41378985b3dc@cs.cmu.edu>

On 15/12/20 15:26, Grant Edwards wrote:
> On 2020-12-15, Mark Polesky via Python-list <python-list at python.org> wrote:
>
>> I see. Perhaps counterintuitive,
> I guess that depends on what programming language you normally think
> in. Python's handling of function parameters is exactly what I
> expected, because all of the previous languages I used did the same
> thing.
>
> Purely out of curiosity, what language had you been using that behaved
> otherwise?
>

R comes to mind; arguments can even be defined as functions of other
arguments, and this is evaluated symbolically at call time:

"""
> f = function(x, y = 2 * x) { y }
> f(1)
[1] 2
> f(2)
[1] 4
> f(y = 3)
[1] 3
"""

MMR...

From loris.bennett at fu-berlin.de  Wed Dec 16 02:59:02 2020
From: loris.bennett at fu-berlin.de (Loris Bennett)
Date: Wed, 16 Dec 2020 08:59:02 +0100
Subject: dict.get(key, default) evaluates default even if key exists
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <rrb0ug$88n$1@ciao.gmane.io>
 <mailman.404.1608059083.7193.python-list@python.org>
Message-ID: <87bleu18s9.fsf@hornfels.zedat.fu-berlin.de>

Serhiy Storchaka <storchaka at gmail.com> writes:

> 15.12.20 19:07, Mark Polesky via Python-list ????:
>> # Running this script....
>> 
>> D = {'a':1}
>> def get_default():
>> ??? print('Nobody expects this')
>> ??? return 0
>> print(D.get('a', get_default()))
>> 
>> # ...generates this output:
>> 
>> Nobody expects this
>> 1
>> 
>> ###
>> 
>> Since I'm brand new to this community, I thought I'd ask here first... Is this
>> worthy of a bug report?? This behavior is definitely unexpected to me, and I
>> accidentally coded an endless loop in a mutual recursion situation because of
>> it.? Calling dict.get.__doc__ only gives this short sentence: Return the value
>> for key if key is in the dictionary, else default.? Nothing in that docstring
>> suggests that the default value is evaluated even if the key exists, and I
>> can't think of any good reason to do so.
>> 
>> Am I missing something?
>
> You are missed that expressions for function arguments are always
> evaluated before passing their values to a function. This is expected
> behavior, and I can't remember any programming language in which it's
> different.
>
> So dict.get() returns the value of argument default, which is computed
> by calling function get_default() before calling dict.get().

Isn't the second argument to D.get() the value to be return if the first
argument is not a valid key?  In that case, why does it make any
difference here what the second argument of D.get() is since the key 'a'
does exist?

Thus, I would indeed expect the code above to print '1'.  I am obviously
missing something here.

Cheers,

Loris

-- 
This signature is currently under construction.

From pbryan at anode.ca  Wed Dec 16 03:41:53 2020
From: pbryan at anode.ca (Paul Bryan)
Date: Wed, 16 Dec 2020 00:41:53 -0800
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <87bleu18s9.fsf@hornfels.zedat.fu-berlin.de>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <rrb0ug$88n$1@ciao.gmane.io>
 <mailman.404.1608059083.7193.python-list@python.org>
 <87bleu18s9.fsf@hornfels.zedat.fu-berlin.de>
Message-ID: <92ed36a3e1fe6a3d3aaf5c935da1dc75402b172b.camel@anode.ca>

On Wed, 2020-12-16 at 08:59 +0100, Loris Bennett wrote:

> Isn't the second argument to D.get() the value to be return if the
> first
> argument is not a valid key?? In that case, why does it make any
> difference here what the second argument of D.get() is since the key
> 'a'
> does exist?
> 
> Thus, I would indeed expect the code above to print '1'.? I am
> obviously
> missing something here.

Yes, the second argument is what to return if there is no valid key.
The second argument is evaluated before the call to the get function.
It's return value is being supplied as an argument to the get function.

Let's write a couple of quick functions to demonstrate...

>>> def get(key, default):
...   print(f"{key=} {default=}")
... 
>>> def generate_a_default_value():
...   return 1
... 
>>> get("a", generate_a_default_value())
key='a' default=1
>>> 

The generate_a_default_value function was called before the call to
get. It was called so it could produce a value that is actually passed
in as an argument to the get function.

Paul


From loris.bennett at fu-berlin.de  Wed Dec 16 04:01:21 2020
From: loris.bennett at fu-berlin.de (Loris Bennett)
Date: Wed, 16 Dec 2020 10:01:21 +0100
Subject: dict.get(key, default) evaluates default even if key exists
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <rrb0ug$88n$1@ciao.gmane.io>
 <mailman.404.1608059083.7193.python-list@python.org>
 <87bleu18s9.fsf@hornfels.zedat.fu-berlin.de>
 <92ed36a3e1fe6a3d3aaf5c935da1dc75402b172b.camel@anode.ca>
 <mailman.419.1608108124.7193.python-list@python.org>
Message-ID: <87pn3ayvj2.fsf@hornfels.zedat.fu-berlin.de>

Paul Bryan <pbryan at anode.ca> writes:

> On Wed, 2020-12-16 at 08:59 +0100, Loris Bennett wrote:
>
>> Isn't the second argument to D.get() the value to be return if the
>> first
>> argument is not a valid key?? In that case, why does it make any
>> difference here what the second argument of D.get() is since the key
>> 'a'
>> does exist?
>> 
>> Thus, I would indeed expect the code above to print '1'.? I am
>> obviously
>> missing something here.
>
> Yes, the second argument is what to return if there is no valid key.
> The second argument is evaluated before the call to the get function.
> It's return value is being supplied as an argument to the get function.
>
> Let's write a couple of quick functions to demonstrate...
>
>>>> def get(key, default):
> ...   print(f"{key=} {default=}")
> ... 
>>>> def generate_a_default_value():
> ...   return 1
> ... 
>>>> get("a", generate_a_default_value())
> key='a' default=1
>>>> 
>
> The generate_a_default_value function was called before the call to
> get. It was called so it could produce a value that is actually passed
> in as an argument to the get function.

OK, I get the point about when the default value is generated and that
potentially being surprising, but in the example originally given, the
key 'a' exists and has a value of '1', so the default value is not
needed.

Thus, I am still unsurprised when dict.get returns the value of an
existing key.

What am I missing?

Cheers,

Loris

-- 
This signature is currently under construction.

From pbryan at anode.ca  Wed Dec 16 04:12:28 2020
From: pbryan at anode.ca (Paul Bryan)
Date: Wed, 16 Dec 2020 01:12:28 -0800
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <87pn3ayvj2.fsf@hornfels.zedat.fu-berlin.de>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <rrb0ug$88n$1@ciao.gmane.io>
 <mailman.404.1608059083.7193.python-list@python.org>
 <87bleu18s9.fsf@hornfels.zedat.fu-berlin.de>
 <92ed36a3e1fe6a3d3aaf5c935da1dc75402b172b.camel@anode.ca>
 <mailman.419.1608108124.7193.python-list@python.org>
 <87pn3ayvj2.fsf@hornfels.zedat.fu-berlin.de>
Message-ID: <05df3a5f53b4d92a34f8399265a84b27f630da96.camel@anode.ca>

On Wed, 2020-12-16 at 10:01 +0100, Loris Bennett wrote:

> OK, I get the point about when the default value is generated and
> that
> potentially being surprising, but in the example originally given,
> the
> key 'a' exists and has a value of '1', so the default value is not
> needed.

But the function is still called. The get method just doesn't use (or
return) the value it generates because the key exists. Nevertheless,
you're passing the return value of the get_default function as an
argument.

> Thus, I am still unsurprised when dict.get returns the value of an
> existing key.

As am I.

> What am I missing?

You'll need to tell me at this point.

Paul


From pbryan at anode.ca  Wed Dec 16 04:38:02 2020
From: pbryan at anode.ca (Paul Bryan)
Date: Wed, 16 Dec 2020 01:38:02 -0800
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <92ed36a3e1fe6a3d3aaf5c935da1dc75402b172b.camel@anode.ca>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <rrb0ug$88n$1@ciao.gmane.io>
 <mailman.404.1608059083.7193.python-list@python.org>
 <87bleu18s9.fsf@hornfels.zedat.fu-berlin.de>
 <92ed36a3e1fe6a3d3aaf5c935da1dc75402b172b.camel@anode.ca>
Message-ID: <8a377abadf168527e5df700b863ff558f3087c85.camel@anode.ca>

Maybe this will help:

>>> def get(key, default):
...   print("entering get")
...   print(f"{key=} {default=}")
...   print("exiting get")
... 
>>> def generate_default():
...   print("entering generate_default")
...   print("exiting generate_default")
...   return 1
... 
>>> get("a", generate_default())
entering generate_default
exiting generate_default
entering get
key='a' default=1
exiting get
>>> 


From loris.bennett at fu-berlin.de  Wed Dec 16 04:36:34 2020
From: loris.bennett at fu-berlin.de (Loris Bennett)
Date: Wed, 16 Dec 2020 10:36:34 +0100
Subject: dict.get(key, default) evaluates default even if key exists
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <rrb0ug$88n$1@ciao.gmane.io>
 <mailman.404.1608059083.7193.python-list@python.org>
 <87bleu18s9.fsf@hornfels.zedat.fu-berlin.de>
 <92ed36a3e1fe6a3d3aaf5c935da1dc75402b172b.camel@anode.ca>
 <mailman.419.1608108124.7193.python-list@python.org>
 <87pn3ayvj2.fsf@hornfels.zedat.fu-berlin.de>
 <05df3a5f53b4d92a34f8399265a84b27f630da96.camel@anode.ca>
 <mailman.420.1608109951.7193.python-list@python.org>
Message-ID: <87lfdyytwd.fsf@hornfels.zedat.fu-berlin.de>

Paul Bryan <pbryan at anode.ca> writes:

> On Wed, 2020-12-16 at 10:01 +0100, Loris Bennett wrote:
>
>> OK, I get the point about when the default value is generated and
>> that
>> potentially being surprising, but in the example originally given,
>> the
>> key 'a' exists and has a value of '1', so the default value is not
>> needed.
>
> But the function is still called. The get method just doesn't use (or
> return) the value it generates because the key exists. Nevertheless,
> you're passing the return value of the get_default function as an
> argument.
>
>> Thus, I am still unsurprised when dict.get returns the value of an
>> existing key.
>
> As am I.
>
>> What am I missing?
>
> You'll need to tell me at this point.

I was just slow and confused, but you helped me get there in the end.  I
now realise that issue is not about the result of the dict.get(), but
rather about the fact that the method which generates the default value
is called, whether or not it is needed.

I shall remember that next time I think it might be a good idea to
define a computationally massively expensive value as a rarely needed
default :-)

Cheers,

Loris

-- 
This signature is currently under construction.

From rosuav at gmail.com  Wed Dec 16 04:44:11 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 16 Dec 2020 20:44:11 +1100
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <87lfdyytwd.fsf@hornfels.zedat.fu-berlin.de>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com> <rrb0ug$88n$1@ciao.gmane.io>
 <mailman.404.1608059083.7193.python-list@python.org>
 <87bleu18s9.fsf@hornfels.zedat.fu-berlin.de>
 <92ed36a3e1fe6a3d3aaf5c935da1dc75402b172b.camel@anode.ca>
 <mailman.419.1608108124.7193.python-list@python.org>
 <87pn3ayvj2.fsf@hornfels.zedat.fu-berlin.de>
 <05df3a5f53b4d92a34f8399265a84b27f630da96.camel@anode.ca>
 <mailman.420.1608109951.7193.python-list@python.org>
 <87lfdyytwd.fsf@hornfels.zedat.fu-berlin.de>
Message-ID: <CAPTjJmqZry5=wD-3GhQ87kHz-EKDJt5V9MiC=8R5pdDEqHidxw@mail.gmail.com>

On Wed, Dec 16, 2020 at 8:43 PM Loris Bennett
<loris.bennett at fu-berlin.de> wrote:
>
> Paul Bryan <pbryan at anode.ca> writes:
>
> > On Wed, 2020-12-16 at 10:01 +0100, Loris Bennett wrote:
> >
> >> OK, I get the point about when the default value is generated and
> >> that
> >> potentially being surprising, but in the example originally given,
> >> the
> >> key 'a' exists and has a value of '1', so the default value is not
> >> needed.
> >
> > But the function is still called. The get method just doesn't use (or
> > return) the value it generates because the key exists. Nevertheless,
> > you're passing the return value of the get_default function as an
> > argument.
> >
> >> Thus, I am still unsurprised when dict.get returns the value of an
> >> existing key.
> >
> > As am I.
> >
> >> What am I missing?
> >
> > You'll need to tell me at this point.
>
> I was just slow and confused, but you helped me get there in the end.  I
> now realise that issue is not about the result of the dict.get(), but
> rather about the fact that the method which generates the default value
> is called, whether or not it is needed.
>
> I shall remember that next time I think it might be a good idea to
> define a computationally massively expensive value as a rarely needed
> default :-)
>

Yep! That's what defaultdict can do - or if you need more flexibility,
subclass dict and add a __missing__ method.

ChrisA

From loris.bennett at fu-berlin.de  Wed Dec 16 04:54:39 2020
From: loris.bennett at fu-berlin.de (Loris Bennett)
Date: Wed, 16 Dec 2020 10:54:39 +0100
Subject: dict.get(key, default) evaluates default even if key exists
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <rrb0ug$88n$1@ciao.gmane.io>
 <mailman.404.1608059083.7193.python-list@python.org>
 <87bleu18s9.fsf@hornfels.zedat.fu-berlin.de>
 <92ed36a3e1fe6a3d3aaf5c935da1dc75402b172b.camel@anode.ca>
 <8a377abadf168527e5df700b863ff558f3087c85.camel@anode.ca>
 <mailman.421.1608111487.7193.python-list@python.org>
Message-ID: <87a6ueyt28.fsf@hornfels.zedat.fu-berlin.de>

Paul Bryan <pbryan at anode.ca> writes:

> Maybe this will help:
>
>>>> def get(key, default):
> ...   print("entering get")
> ...   print(f"{key=} {default=}")
> ...   print("exiting get")
> ... 
>>>> def generate_default():
> ...   print("entering generate_default")
> ...   print("exiting generate_default")
> ...   return 1
> ... 
>>>> get("a", generate_default())
> entering generate_default
> exiting generate_default
> entering get
> key='a' default=1
> exiting get
>>>> 

OK, so it even has nothing to do with dict.get().  It is just about the
way function arguments are evaluated.  Your example above illustrates
nicely that Python does what I would expect, although from the examples
others have given, I might have to adjust my expectations when using
other languages.

Cheers,

Loris

-- 
This signature is currently under construction.

From hjp-python at hjp.at  Wed Dec 16 06:08:23 2020
From: hjp-python at hjp.at (Peter J. Holzer)
Date: Wed, 16 Dec 2020 12:08:23 +0100
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <3f9bf105-1909-3b3a-4823-eaa450a1a2ec@stoneleaf.us>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <3f9bf105-1909-3b3a-4823-eaa450a1a2ec@stoneleaf.us>
Message-ID: <20201216110823.GA27513@hjp.at>

On 2020-12-15 13:07:25 -0800, Ethan Furman wrote:
> On 12/15/20 9:07 AM, Mark Polesky via Python-list wrote:
> 
> > D = {'a':1}
> >
> > def get_default():
> >      print('Nobody expects this')
> >      return 0
> >
> > print(D.get('a', get_default()))
> 
> Python has short-circuiting logical operations, so one way to get the behavior you're looking for is:
> 
>     D.get('a') or get_default()

That will call get_default for any falsey value (0, "", an empty list ...),
not just for missing values.

Which may or may not be what the OP wants.

        hp

-- 
   _  | Peter J. Holzer    | Story must make more sense than reality.
|_|_) |                    |
| |   | hjp at hjp.at         |    -- Charles Stross, "Creative writing
__/   | http://www.hjp.at/ |       challenge!"
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From rosuav at gmail.com  Wed Dec 16 06:26:52 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 16 Dec 2020 22:26:52 +1100
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <20201216110823.GA27513@hjp.at>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <3f9bf105-1909-3b3a-4823-eaa450a1a2ec@stoneleaf.us>
 <20201216110823.GA27513@hjp.at>
Message-ID: <CAPTjJmqDf7aSv_PvLSpqW-Re9NBaWrA8iAecGXCkhLZT7wODhQ@mail.gmail.com>

On Wed, Dec 16, 2020 at 10:17 PM Peter J. Holzer <hjp-python at hjp.at> wrote:
>
> On 2020-12-15 13:07:25 -0800, Ethan Furman wrote:
> > On 12/15/20 9:07 AM, Mark Polesky via Python-list wrote:
> >
> > > D = {'a':1}
> > >
> > > def get_default():
> > >      print('Nobody expects this')
> > >      return 0
> > >
> > > print(D.get('a', get_default()))
> >
> > Python has short-circuiting logical operations, so one way to get the behavior you're looking for is:
> >
> >     D.get('a') or get_default()
>
> That will call get_default for any falsey value (0, "", an empty list ...),
> not just for missing values.
>
> Which may or may not be what the OP wants.
>

D['a'] if 'a' in D else get_default()

ChrisA

From rshepard at appl-ecosys.com  Wed Dec 16 08:39:06 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Wed, 16 Dec 2020 05:39:06 -0800 (PST)
Subject: Python3 change logs
In-Reply-To: <rrbsoo$13fn$1@ciao.gmane.io>
References: <alpine.LNX.2.20.2012150749530.32731@salmo.appl-ecosys.com>
 <CANc-5UygZkZR852emcjQDjJ2wovY0tjQBmzRYHGarqz3U0=NXQ@mail.gmail.com>
 <CANc-5UzmVxq5GQp4hK3ATPbtp4Bmb7CCKjG7_dLWWUoqzoZ2hQ@mail.gmail.com>
 <CANc-5UxF3dcpxQ8eYCT9__8Xmw2dfsc-ZT=0-hOMky1oHv7ouQ@mail.gmail.com>
 <rrbsoo$13fn$1@ciao.gmane.io>
Message-ID: <alpine.LNX.2.20.2012160538430.21010@salmo.appl-ecosys.com>

On Tue, 15 Dec 2020, Terry Reedy wrote:

> In particular, for latest release (now 3.9) you would want tkinter in
> https://docs.python.org/3/whatsnew/3.9.html#improved-modules but nothing
> there. However, https://docs.python.org/3.8/whatsnew/3.8.html#tkinter

Thanks, Terry.

Stay well,

Rich

From robert.rosengard at gmail.com  Wed Dec 16 11:04:11 2020
From: robert.rosengard at gmail.com (Rob Rosengard)
Date: Wed, 16 Dec 2020 08:04:11 -0800 (PST)
Subject: Python concurrent.futures.ProcessPoolExecutor
Message-ID: <e0f990d1-c3d6-4062-84f4-c67b10d5730an@googlegroups.com>

Warning:  I am new to this group
Warning:  I am not an expert at Python, I've written a few small programs, and spend 20 hours of online classes, and maybe a book or two. 
Warning:  I am new to trying to use concurrent.futures.ProcessPoolExecutor
- Prior to writing this question I updated to Python 3.9 and PyCharm 2020.3.  And confirmed the problem still exists. 
- Running on Windows 10 Professional
- I've been trying to run a simple piece of code to exactly match what I have seen done in various training videos.  By I am getting a different and 
unexpected set of results.  I.e. the instructor got different results than I did on my computer.  My code is very simple:

import concurrent.futures
import time


start = time.perf_counter()


def task(myarg):
    print(f'Sleeping one second...{myarg}')
    time.sleep(1)
    return 'Done sleeping...'


if __name__ == '__main__':
    with concurrent.futures.ProcessPoolExecutor() as executor:
        future1 = executor.submit(task, 1)
        future2 = executor.submit(task, 2)
finish = time.perf_counter()
print(f'Finished in {round(finish-start,2)} seconds')

And the output is: 
Finished in 0.0 seconds
Finished in 0.0 seconds
Sleeping one second...1
Sleeping one second...2
Finished in 1.14 seconds

Process finished with exit code 0

--- 
QUESTIONS and CONCERNS that I have...
It seems that both calls to task not only runs that function, but then keeps executing the rest of the main line code.  I only expected it to run the function and then immediately quit/disappear.   That is, I expect the output to look like (i.e. not having the three lines of "Finished in x.x seconds", rather, just one line like that):
Sleeping one second...1
Sleeping one second...2
Finished in 1.14 seconds

Goal:  I need the executor tasks to only run that one function, and then completely go away and stop.  Not keep executing more code that doesn't belong to the task function. 

I've tried many iterations of this issue, and placed PRINT statements all over to try to track what is going on.  And I used if/else statements in the main code, which caused even more problems.  I.e. both the IF and the ELSE was executed each time through the code. Which completely blows my mind. 

Any thoughts on this?  Thanks for your time and help!  

R

From ethan at stoneleaf.us  Wed Dec 16 11:59:31 2020
From: ethan at stoneleaf.us (Ethan Furman)
Date: Wed, 16 Dec 2020 08:59:31 -0800
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <CAPTjJmqZry5=wD-3GhQ87kHz-EKDJt5V9MiC=8R5pdDEqHidxw@mail.gmail.com>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com> <rrb0ug$88n$1@ciao.gmane.io>
 <mailman.404.1608059083.7193.python-list@python.org>
 <87bleu18s9.fsf@hornfels.zedat.fu-berlin.de>
 <92ed36a3e1fe6a3d3aaf5c935da1dc75402b172b.camel@anode.ca>
 <mailman.419.1608108124.7193.python-list@python.org>
 <87pn3ayvj2.fsf@hornfels.zedat.fu-berlin.de>
 <05df3a5f53b4d92a34f8399265a84b27f630da96.camel@anode.ca>
 <mailman.420.1608109951.7193.python-list@python.org>
 <87lfdyytwd.fsf@hornfels.zedat.fu-berlin.de>
 <CAPTjJmqZry5=wD-3GhQ87kHz-EKDJt5V9MiC=8R5pdDEqHidxw@mail.gmail.com>
Message-ID: <09aee7aa-146c-1c7f-1d0e-b800d7f4eac5@stoneleaf.us>

On 12/16/20 1:44 AM, Chris Angelico wrote:
> On Wed, Dec 16, 2020 at 8:43 PM Loris Bennett
> <loris.bennett at fu-berlin.de> wrote:
>>
>> Paul Bryan <pbryan at anode.ca> writes:
>>
>>> On Wed, 2020-12-16 at 10:01 +0100, Loris Bennett wrote:
>>>
>>>> OK, I get the point about when the default value is generated and
>>>> that
>>>> potentially being surprising, but in the example originally given,
>>>> the
>>>> key 'a' exists and has a value of '1', so the default value is not
>>>> needed.
>>>
>>> But the function is still called. The get method just doesn't use (or
>>> return) the value it generates because the key exists. Nevertheless,
>>> you're passing the return value of the get_default function as an
>>> argument.
>>>
>>>> Thus, I am still unsurprised when dict.get returns the value of an
>>>> existing key.
>>>
>>> As am I.
>>>
>>>> What am I missing?
>>>
>>> You'll need to tell me at this point.
>>
>> I was just slow and confused, but you helped me get there in the end.  I
>> now realise that issue is not about the result of the dict.get(), but
>> rather about the fact that the method which generates the default value
>> is called, whether or not it is needed.
>>
>> I shall remember that next time I think it might be a good idea to
>> define a computationally massively expensive value as a rarely needed
>> default :-)
>>
> 
> Yep! That's what defaultdict can do - or if you need more flexibility,
> subclass dict and add a __missing__ method.

Or, if the computationally massively expensive call uses potentially
different arguments for each invocation:

     some_var = d.get('a') or cme(arg1, arg2, ...)

--
~Ethan~

From ethan at stoneleaf.us  Wed Dec 16 12:06:48 2020
From: ethan at stoneleaf.us (Ethan Furman)
Date: Wed, 16 Dec 2020 09:06:48 -0800
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <20201216110823.GA27513@hjp.at>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <3f9bf105-1909-3b3a-4823-eaa450a1a2ec@stoneleaf.us>
 <20201216110823.GA27513@hjp.at>
Message-ID: <23916595-bcbe-0db1-9f75-6f85cb95bb9a@stoneleaf.us>

On 12/16/20 3:08 AM, Peter J. Holzer wrote:
> On 2020-12-15 13:07:25 -0800, Ethan Furman wrote:
>> On 12/15/20 9:07 AM, Mark Polesky via Python-list wrote:
>>
>>> D = {'a':1}
>>>
>>> def get_default():
>>>       print('Nobody expects this')
>>>       return 0
>>>
>>> print(D.get('a', get_default()))
>>
>> Python has short-circuiting logical operations, so one way to get the behavior you're looking for is:
>>
>>      D.get('a') or get_default()
> 
> That will call get_default for any falsey value (0, "", an empty list ...),
> not just for missing values.
> 
> Which may or may not be what the OP wants.

Good point, thanks for clarifying.

--
~Ethan~

From ijbrewster at alaska.edu  Wed Dec 16 12:22:12 2020
From: ijbrewster at alaska.edu (Israel Brewster)
Date: Wed, 16 Dec 2020 08:22:12 -0900
Subject: Python concurrent.futures.ProcessPoolExecutor
In-Reply-To: <e0f990d1-c3d6-4062-84f4-c67b10d5730an@googlegroups.com>
References: <e0f990d1-c3d6-4062-84f4-c67b10d5730an@googlegroups.com>
Message-ID: <5550C8CA-A679-40FF-8389-FC4A2C3FD2B4@alaska.edu>

> On Dec 16, 2020, at 7:04 AM, Rob Rosengard <robert.rosengard at gmail.com> wrote:
> 
> Warning:  I am new to this group
> Warning:  I am not an expert at Python, I've written a few small programs, and spend 20 hours of online classes, and maybe a book or two. 
> Warning:  I am new to trying to use concurrent.futures.ProcessPoolExecutor
> - Prior to writing this question I updated to Python 3.9 and PyCharm 2020.3.  And confirmed the problem still exists. 
> - Running on Windows 10 Professional
> - I've been trying to run a simple piece of code to exactly match what I have seen done in various training videos.  By I am getting a different and 
> unexpected set of results.  I.e. the instructor got different results than I did on my computer.  My code is very simple:
> 
> import concurrent.futures
> import time
> 
> 
> start = time.perf_counter()
> 
> 
> def task(myarg):
>    print(f'Sleeping one second...{myarg}')
>    time.sleep(1)
>    return 'Done sleeping...'
> 
> 
> if __name__ == '__main__':
>    with concurrent.futures.ProcessPoolExecutor() as executor:
>        future1 = executor.submit(task, 1)
>        future2 = executor.submit(task, 2)
> finish = time.perf_counter()
> print(f'Finished in {round(finish-start,2)} seconds')
> 
> And the output is: 
> Finished in 0.0 seconds
> Finished in 0.0 seconds
> Sleeping one second...1
> Sleeping one second...2
> Finished in 1.14 seconds
> 
> Process finished with exit code 0
> 
> --- 
> QUESTIONS and CONCERNS that I have...
> It seems that both calls to task not only runs that function, but then keeps executing the rest of the main line code.  I only expected it to run the function and then immediately quit/disappear.   That is, I expect the output to look like (i.e. not having the three lines of "Finished in x.x seconds", rather, just one line like that):
> Sleeping one second...1
> Sleeping one second...2
> Finished in 1.14 seconds
> 
> Goal:  I need the executor tasks to only run that one function, and then completely go away and stop.  Not keep executing more code that doesn't belong to the task function. 
> 
> I've tried many iterations of this issue, and placed PRINT statements all over to try to track what is going on.  And I used if/else statements in the main code, which caused even more problems.  I.e. both the IF and the ELSE was executed each time through the code. Which completely blows my mind. 
> 
> Any thoughts on this?  Thanks for your time and help!  

Assuming the code above is indented exactly as you run it, you have an indentation error. That is, the finish and print() are not indented to be part of the if __name__? call. As such, they run on import. When you launch a new process, it imports the module, which then runs those lines, since they are not guarded by the if statement.

Indent those last two lines to be under the if (they don?t need to be indented to be under the with, just the if), and it should work as intended.

---
Israel Brewster
Software Engineer
Alaska Volcano Observatory 
Geophysical Institute - UAF 
2156 Koyukuk Drive 
Fairbanks AK 99775-7320
Work: 907-474-5172
cell:  907-328-9145

> 
> R
> -- 
> https://mail.python.org/mailman/listinfo/python-list


From drsalists at gmail.com  Wed Dec 16 12:49:52 2020
From: drsalists at gmail.com (Dan Stromberg)
Date: Wed, 16 Dec 2020 09:49:52 -0800
Subject: Python concurrent.futures.ProcessPoolExecutor
In-Reply-To: <5550C8CA-A679-40FF-8389-FC4A2C3FD2B4@alaska.edu>
References: <e0f990d1-c3d6-4062-84f4-c67b10d5730an@googlegroups.com>
 <5550C8CA-A679-40FF-8389-FC4A2C3FD2B4@alaska.edu>
Message-ID: <CAGGBd_qPTEMGH=YMfyP4G2j9Mbcr4=B3o7KV_kELHWD5uqRY2A@mail.gmail.com>

On Wed, Dec 16, 2020 at 9:23 AM Israel Brewster <ijbrewster at alaska.edu>
wrote:

> > On Dec 16, 2020, at 7:04 AM, Rob Rosengard <robert.rosengard at gmail.com>
> wrote:
> >
> > Warning:  I am new to this group
> > Warning:  I am not an expert at Python, I've written a few small
> programs, and spend 20 hours of online classes, and maybe a book or two.
> > Warning:  I am new to trying to use
> concurrent.futures.ProcessPoolExecutor
> > - Prior to writing this question I updated to Python 3.9 and PyCharm
> 2020.3.  And confirmed the problem still exists.
> > - Running on Windows 10 Professional
> > - I've been trying to run a simple piece of code to exactly match what I
> have seen done in various training videos.  By I am getting a different and
> > unexpected set of results.  I.e. the instructor got different results
> than I did on my computer.  My code is very simple:
> >
> > import concurrent.futures
> > import time
> >
> >
> > start = time.perf_counter()
> >
> >
> > def task(myarg):
> >    print(f'Sleeping one second...{myarg}')
> >    time.sleep(1)
> >    return 'Done sleeping...'
> >
> >
> > if __name__ == '__main__':
> >    with concurrent.futures.ProcessPoolExecutor() as executor:
> >        future1 = executor.submit(task, 1)
> >        future2 = executor.submit(task, 2)
> > finish = time.perf_counter()
> > print(f'Finished in {round(finish-start,2)} seconds')
> >
> > And the output is:
> > Finished in 0.0 seconds
> > Finished in 0.0 seconds
> > Sleeping one second...1
> > Sleeping one second...2
> > Finished in 1.14 seconds
> >
> > Process finished with exit code 0
>


> Assuming the code above is indented exactly as you run it, you have an
> indentation error. That is, the finish and print() are not indented to be
> part of the if __name__? call. As such, they run on import. When you launch
> a new process, it imports the module, which then runs those lines, since
> they are not guarded by the if statement.
>
> Indent those last two lines to be under the if (they don?t need to be
> indented to be under the with, just the if), and it should work as intended.
>

Windows has a problem forking, so the indentation is more persnickety
there. On Linux and I believe on Mac, you don't have to be so careful with
multiprocessing and concurrent.futures.

From python at mrabarnett.plus.com  Wed Dec 16 12:51:53 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Wed, 16 Dec 2020 17:51:53 +0000
Subject: Python concurrent.futures.ProcessPoolExecutor
In-Reply-To: <e0f990d1-c3d6-4062-84f4-c67b10d5730an@googlegroups.com>
References: <e0f990d1-c3d6-4062-84f4-c67b10d5730an@googlegroups.com>
Message-ID: <391d74a8-9371-59be-42a1-f7c36dfbf145@mrabarnett.plus.com>

On 2020-12-16 16:04, Rob Rosengard wrote:
> Warning:  I am new to this group
> Warning:  I am not an expert at Python, I've written a few small programs, and spend 20 hours of online classes, and maybe a book or two.
> Warning:  I am new to trying to use concurrent.futures.ProcessPoolExecutor
> - Prior to writing this question I updated to Python 3.9 and PyCharm 2020.3.  And confirmed the problem still exists.
> - Running on Windows 10 Professional
> - I've been trying to run a simple piece of code to exactly match what I have seen done in various training videos.  By I am getting a different and
> unexpected set of results.  I.e. the instructor got different results than I did on my computer.  My code is very simple:
> 
> import concurrent.futures
> import time
> 
> 
> start = time.perf_counter()
> 
> 
> def task(myarg):
>      print(f'Sleeping one second...{myarg}')
>      time.sleep(1)
>      return 'Done sleeping...'
> 
> 
> if __name__ == '__main__':
>      with concurrent.futures.ProcessPoolExecutor() as executor:
>          future1 = executor.submit(task, 1)
>          future2 = executor.submit(task, 2)
> finish = time.perf_counter()
> print(f'Finished in {round(finish-start,2)} seconds')
> 
> And the output is:
> Finished in 0.0 seconds
> Finished in 0.0 seconds
> Sleeping one second...1
> Sleeping one second...2
> Finished in 1.14 seconds
> 
> Process finished with exit code 0
> 
> ---
> QUESTIONS and CONCERNS that I have...
> It seems that both calls to task not only runs that function, but then keeps executing the rest of the main line code.  I only expected it to run the function and then immediately quit/disappear.   That is, I expect the output to look like (i.e. not having the three lines of "Finished in x.x seconds", rather, just one line like that):
> Sleeping one second...1
> Sleeping one second...2
> Finished in 1.14 seconds
> 
> Goal:  I need the executor tasks to only run that one function, and then completely go away and stop.  Not keep executing more code that doesn't belong to the task function.
> 
> I've tried many iterations of this issue, and placed PRINT statements all over to try to track what is going on.  And I used if/else statements in the main code, which caused even more problems.  I.e. both the IF and the ELSE was executed each time through the code. Which completely blows my mind.
> 
> Any thoughts on this?  Thanks for your time and help!
> 
It imports the module to run the function, so any top-level code _will_ 
be run.

Here's a modified version:

--8<----------------------------8<--

import concurrent.futures
import time

print('Main code, __name__ is {!a}'.format(__name__))

start = time.perf_counter()


def task(myarg):
     print('In task, __name__ is {!a}'.format(__name__))
     print(f'Sleeping one second...{myarg}')
     time.sleep(1)
     return 'Done sleeping...'


if __name__ == '__main__':
     with concurrent.futures.ProcessPoolExecutor() as executor:
         future1 = executor.submit(task, 1)
         future2 = executor.submit(task, 2)
finish = time.perf_counter()
print(f'Finished in {round(finish-start,2)} seconds')

--8<----------------------------8<--

It prints:

--8<----------------------------8<--

Main code, __name__ is '__main__'
Main code, __name__ is '__mp_main__'
Finished in 0.0 seconds
Main code, __name__ is '__mp_main__'
Finished in 0.0 seconds
In task, __name__ is '__mp_main__'
Sleeping one second...1
In task, __name__ is '__mp_main__'
Sleeping one second...2
Finished in 1.8 seconds

--8<----------------------------8<--

Any top-level code that you don't want it to run when it re-imports the 
module should be protected by the __name__ test.

From willum97 at gmail.com  Wed Dec 16 12:15:57 2020
From: willum97 at gmail.com (Erick Willum)
Date: Wed, 16 Dec 2020 17:15:57 +0000
Subject: Fwd: bug in download
References: <CAKm_qBoW9mm-=goPy49iPXAquagjmx9DR2OVz25DMuaM2wHOrw@mail.gmail.com>
Message-ID: <02A2815D-8377-4A65-AB47-B67FE33B6D07@gmail.com>




Begin forwarded message:

> From: Erick Willum <willum97 at gmail.com>
> Date: 16 December 2020 at 15:53:40 GMT
> To: python-list at python.org
> Subject: bug in download
> 
> Hallo and good afternoon,
> 
> Having installed python (big thank you) and sublime text, i get the next message when trying to download numpy or matplotlib in sublime text:
> 
> fails to pass a sanity check due to a bug in the windows runtime. See this issue for more information: 
> https://tinyurl.com/y3dm3h86I
> 
> I got the next message from tiny.url, the long url is:
> 
> https://developercommunity.visualstudio.com/content/problem/
> 1207405/fmod-after-an-update-to-windows-2004-is-causing-a.html
> 
> These next lines appear in the sublime window as well:
> 
>   File "C:\Users\Bill\AppData\Local\Programs\Python\Python39\lib\site-packages\numpy\__init__.py", line 305, in <module>
>     _win_os_check()
>   File "C:\Users\Bill\AppData\Local\Programs\Python\Python39\lib\site-packages\numpy\__init__.py", line 302, in _win_os_check
>     raise RuntimeError(msg.format(__file__)) from None
> 
> I would appreciate your help.
> Thanks again.
> Bill.
> 
> 

From cl at isbd.net  Wed Dec 16 13:51:54 2020
From: cl at isbd.net (Chris Green)
Date: Wed, 16 Dec 2020 18:51:54 +0000
Subject: Python 2 to Python 3 .so library incompatibility - need help
Message-ID: <aj1qah-olf.ln1@esprimo.zbmc.eu>

Some time ago (in July) I asked some questions here
about problems migrating some code from Python 2 to Python 3.  

The specific problem that finally prevented me from managing to get it
to work was a (Linux) .so file that had been built for Python 2 and,
as I don't have the source, I can't build for Python 3.

I need to have another go at fixing this as otherwise the code that I
need to manage my printer will stop working as I update my Ubuntu
systems.

The specific error I'm getting is as follows:-

    File "/usr/libexec/okimfputl.new/guicom.py", line 66, in <module> import pyscand
    ImportError: /usr/libexec/okimfpdrv/pyscand.so: undefined symbol: _Py_ZeroStruct

I know this is because the extension module is compiled for Python 2
and _Py_ZeroStruct is only available in Python 2.  I don't have the C
code for the module. 

Is there *any* other way around this, like a 'compatibility module' to
use Python 2 .so files in Python 3 or anything like it?  I have all
the Python code and have (up to hitting this problem) converted it to
Python 3.


-- 
Chris Green
?

From rosuav at gmail.com  Wed Dec 16 14:16:23 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 17 Dec 2020 06:16:23 +1100
Subject: Python 2 to Python 3 .so library incompatibility - need help
In-Reply-To: <aj1qah-olf.ln1@esprimo.zbmc.eu>
References: <aj1qah-olf.ln1@esprimo.zbmc.eu>
Message-ID: <CAPTjJmrNBneT+Wwjz7JMSRJXLomPCKMNw_vL75x9EiHNffvw1g@mail.gmail.com>

On Thu, Dec 17, 2020 at 6:06 AM Chris Green <cl at isbd.net> wrote:
>
> Some time ago (in July) I asked some questions here
> about problems migrating some code from Python 2 to Python 3.
>
> The specific problem that finally prevented me from managing to get it
> to work was a (Linux) .so file that had been built for Python 2 and,
> as I don't have the source, I can't build for Python 3.
>
> I need to have another go at fixing this as otherwise the code that I
> need to manage my printer will stop working as I update my Ubuntu
> systems.
>
> The specific error I'm getting is as follows:-
>
>     File "/usr/libexec/okimfputl.new/guicom.py", line 66, in <module> import pyscand
>     ImportError: /usr/libexec/okimfpdrv/pyscand.so: undefined symbol: _Py_ZeroStruct
>
> I know this is because the extension module is compiled for Python 2
> and _Py_ZeroStruct is only available in Python 2.  I don't have the C
> code for the module.
>
> Is there *any* other way around this, like a 'compatibility module' to
> use Python 2 .so files in Python 3 or anything like it?  I have all
> the Python code and have (up to hitting this problem) converted it to
> Python 3.
>

Basically no. The error you're seeing is a nice noisy one, but even if
you got past that, there'll be a LOT of incompatibilities.
Unfortunately, a quick google search for 'pyscand' showed up....
places where you've asked this question, suggesting that nobody else
uses this library. It looks like you're going to have to take a big
step back and figure out what the library is doing for you, and
reimplement that somehow. :(

Good luck.

ChrisA

From grant.b.edwards at gmail.com  Wed Dec 16 14:31:23 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Wed, 16 Dec 2020 19:31:23 -0000 (UTC)
Subject: dict.get(key, default) evaluates default even if key exists
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <rrb0ug$88n$1@ciao.gmane.io>
 <1823740026.830499.1608062933098@mail.yahoo.com>
 <t0hktf5lcbm4k3fjfj5na5tnvp2k87kdpj@4ax.com>
Message-ID: <rrdnab$361$1@ciao.gmane.io>

On 2020-12-16, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
> On Tue, 15 Dec 2020 20:08:53 +0000 (UTC), Mark Polesky via Python-list
><python-list at python.org> declaimed the following:
>
>>behavior, and I can't remember any programming language in which it's
>>different.
>
> https://en.wikipedia.org/wiki/Evaluation_strategy#Call_by_name 

Most of us only run across call-by-name when using macro processors
(cpp, m4, TeX, various assemblers). I vaguely recall some other old
language I ran across in a survey course when in college that used it.
IIRC it was Algol. Somebody else already mentioned Haskel.

--
Grant








From tjreedy at udel.edu  Wed Dec 16 14:46:14 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 16 Dec 2020 14:46:14 -0500
Subject: Fwd: bug in download
In-Reply-To: <02A2815D-8377-4A65-AB47-B67FE33B6D07@gmail.com>
References: <CAKm_qBoW9mm-=goPy49iPXAquagjmx9DR2OVz25DMuaM2wHOrw@mail.gmail.com>
 <02A2815D-8377-4A65-AB47-B67FE33B6D07@gmail.com>
Message-ID: <rrdo67$v41$1@ciao.gmane.io>

On 12/16/2020 12:15 PM, Erick Willum wrote:
> 
> 
> 
> Begin forwarded message:
> 
>> From: Erick Willum <willum97 at gmail.com>
>> Date: 16 December 2020 at 15:53:40 GMT
>> To: python-list at python.org
>> Subject: bug in download
>>
>> Hallo and good afternoon,
>>
>> Having installed python (big thank you) and sublime text, i get the next message when trying to download numpy or matplotlib in sublime text:
>>
>> fails to pass a sanity check due to a bug in the windows runtime. See this issue for more information:
>> https://tinyurl.com/y3dm3h86I

The answer on stackoverflow.com, easily accessed by their local search 
or Google web search: use 1.9.3 on Windows 2004, 1.9.4 on *nix.  1.9.3 
did not work on *nix, and the 1.9.4 hotfix does not work on on some 
Windows.  I have not seen anything either way about the 2009 Windows update

-- 
Terry Jan Reedy


From python at mrabarnett.plus.com  Wed Dec 16 15:22:40 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Wed, 16 Dec 2020 20:22:40 +0000
Subject: Python 2 to Python 3 .so library incompatibility - need help
In-Reply-To: <CAPTjJmrNBneT+Wwjz7JMSRJXLomPCKMNw_vL75x9EiHNffvw1g@mail.gmail.com>
References: <aj1qah-olf.ln1@esprimo.zbmc.eu>
 <CAPTjJmrNBneT+Wwjz7JMSRJXLomPCKMNw_vL75x9EiHNffvw1g@mail.gmail.com>
Message-ID: <1da544bc-3e69-cc16-5f78-8a3dad402064@mrabarnett.plus.com>

On 2020-12-16 19:16, Chris Angelico wrote:
> On Thu, Dec 17, 2020 at 6:06 AM Chris Green <cl at isbd.net> wrote:
>>
>> Some time ago (in July) I asked some questions here
>> about problems migrating some code from Python 2 to Python 3.
>>
>> The specific problem that finally prevented me from managing to get it
>> to work was a (Linux) .so file that had been built for Python 2 and,
>> as I don't have the source, I can't build for Python 3.
>>
>> I need to have another go at fixing this as otherwise the code that I
>> need to manage my printer will stop working as I update my Ubuntu
>> systems.
>>
>> The specific error I'm getting is as follows:-
>>
>>     File "/usr/libexec/okimfputl.new/guicom.py", line 66, in <module> import pyscand
>>     ImportError: /usr/libexec/okimfpdrv/pyscand.so: undefined symbol: _Py_ZeroStruct
>>
>> I know this is because the extension module is compiled for Python 2
>> and _Py_ZeroStruct is only available in Python 2.  I don't have the C
>> code for the module.
>>
>> Is there *any* other way around this, like a 'compatibility module' to
>> use Python 2 .so files in Python 3 or anything like it?  I have all
>> the Python code and have (up to hitting this problem) converted it to
>> Python 3.
>>
> 
> Basically no. The error you're seeing is a nice noisy one, but even if
> you got past that, there'll be a LOT of incompatibilities.
> Unfortunately, a quick google search for 'pyscand' showed up....
> places where you've asked this question, suggesting that nobody else
> uses this library. It looks like you're going to have to take a big
> step back and figure out what the library is doing for you, and
> reimplement that somehow. :(
> 
> Good luck.
> 
Alternatively, run something in Python 2.7 that can import it and talk 
to the main Python 3 code, at least until you have a long-term solution.

From rosuav at gmail.com  Wed Dec 16 15:32:20 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 17 Dec 2020 07:32:20 +1100
Subject: Python 2 to Python 3 .so library incompatibility - need help
In-Reply-To: <1da544bc-3e69-cc16-5f78-8a3dad402064@mrabarnett.plus.com>
References: <aj1qah-olf.ln1@esprimo.zbmc.eu>
 <CAPTjJmrNBneT+Wwjz7JMSRJXLomPCKMNw_vL75x9EiHNffvw1g@mail.gmail.com>
 <1da544bc-3e69-cc16-5f78-8a3dad402064@mrabarnett.plus.com>
Message-ID: <CAPTjJmqxTYkQwaO2SMEmMRLnbkm+zePG00xTnwr371xmk6e4vg@mail.gmail.com>

On Thu, Dec 17, 2020 at 7:27 AM MRAB <python at mrabarnett.plus.com> wrote:
>
> On 2020-12-16 19:16, Chris Angelico wrote:
> > On Thu, Dec 17, 2020 at 6:06 AM Chris Green <cl at isbd.net> wrote:
> >>
> >> Some time ago (in July) I asked some questions here
> >> about problems migrating some code from Python 2 to Python 3.
> >>
> >> The specific problem that finally prevented me from managing to get it
> >> to work was a (Linux) .so file that had been built for Python 2 and,
> >> as I don't have the source, I can't build for Python 3.
> >>
> >> I need to have another go at fixing this as otherwise the code that I
> >> need to manage my printer will stop working as I update my Ubuntu
> >> systems.
> >>
> >> The specific error I'm getting is as follows:-
> >>
> >>     File "/usr/libexec/okimfputl.new/guicom.py", line 66, in <module> import pyscand
> >>     ImportError: /usr/libexec/okimfpdrv/pyscand.so: undefined symbol: _Py_ZeroStruct
> >>
> >> I know this is because the extension module is compiled for Python 2
> >> and _Py_ZeroStruct is only available in Python 2.  I don't have the C
> >> code for the module.
> >>
> >> Is there *any* other way around this, like a 'compatibility module' to
> >> use Python 2 .so files in Python 3 or anything like it?  I have all
> >> the Python code and have (up to hitting this problem) converted it to
> >> Python 3.
> >>
> >
> > Basically no. The error you're seeing is a nice noisy one, but even if
> > you got past that, there'll be a LOT of incompatibilities.
> > Unfortunately, a quick google search for 'pyscand' showed up....
> > places where you've asked this question, suggesting that nobody else
> > uses this library. It looks like you're going to have to take a big
> > step back and figure out what the library is doing for you, and
> > reimplement that somehow. :(
> >
> > Good luck.
> >
> Alternatively, run something in Python 2.7 that can import it and talk
> to the main Python 3 code, at least until you have a long-term solution.

Yes, that's a possibility. A hack, but a definite hack. But this is
one of the places where the universality of stdin/stdout is extremely
handy.

ChrisA

From cs at cskk.id.au  Wed Dec 16 16:24:47 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Thu, 17 Dec 2020 08:24:47 +1100
Subject: Python 2 to Python 3 .so library incompatibility - need help
In-Reply-To: <aj1qah-olf.ln1@esprimo.zbmc.eu>
References: <aj1qah-olf.ln1@esprimo.zbmc.eu>
Message-ID: <20201216212447.GA22531@cskk.homeip.net>

On 16Dec2020 18:51, Chris Green <cl at isbd.net> wrote:
>The specific problem that finally prevented me from managing to get it
>to work was a (Linux) .so file that had been built for Python 2 and,
>as I don't have the source, I can't build for Python 3.

ChrisA I think suggested keeping a Python 2.7 install around for this.

>I need to have another go at fixing this as otherwise the code that I
>need to manage my printer will stop working as I update my Ubuntu
>systems.

Have you considered keeping a legacy VM around as well? I have a few VMs 
sitting here I use for some legacy software.

Have you checked an upgraded Ubuntu to failure to run your software 
using Python 2? Python 2 won't be installed by default, but I'm pretty 
sure you can add it in. It is just the "system Python" which is moving 
to Python 3.

Also, make note of the specific Python 2 version where your software 
works - the CPython API does change somewhat sometimes.

>The specific error I'm getting is as follows:-
>    File "/usr/libexec/okimfputl.new/guicom.py", line 66, in <module> import pyscand
>    ImportError: /usr/libexec/okimfpdrv/pyscand.so: undefined symbol: _Py_ZeroStruct


Guessing from the library name, have you looked on the OKI.com site for 
current software? Maybe here? What's your printer model?

    https://www.oki.com/au/printing/support/drivers-and-utilities/index.html

Not that I've found anything helpful...

What Ubuntu package supplies that .so file?

>Is there *any* other way around this, like a 'compatibility module' to
>use Python 2 .so files in Python 3 or anything like it?  I have all
>the Python code and have (up to hitting this problem) converted it to
>Python 3.

Almost certainly not. I think ChrisA's Python 2 suggestion is the go 
here.

You may need to manually copy the requisite .so files if the package is 
about to vanish.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From rosuav at gmail.com  Wed Dec 16 16:32:11 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 17 Dec 2020 08:32:11 +1100
Subject: Python 2 to Python 3 .so library incompatibility - need help
In-Reply-To: <20201216212447.GA22531@cskk.homeip.net>
References: <aj1qah-olf.ln1@esprimo.zbmc.eu>
 <20201216212447.GA22531@cskk.homeip.net>
Message-ID: <CAPTjJmp26DUVxg8aH56bsuOyWg4FLcpOdHLX6eO47_H2ZE7xrQ@mail.gmail.com>

On Thu, Dec 17, 2020 at 8:26 AM Cameron Simpson <cs at cskk.id.au> wrote:
>
> On 16Dec2020 18:51, Chris Green <cl at isbd.net> wrote:
> >The specific problem that finally prevented me from managing to get it
> >to work was a (Linux) .so file that had been built for Python 2 and,
> >as I don't have the source, I can't build for Python 3.
>
> ChrisA I think suggested keeping a Python 2.7 install around for this.

(MRAB did, but I agree with it.)

ChrisA

From cl at isbd.net  Wed Dec 16 16:59:17 2020
From: cl at isbd.net (Chris Green)
Date: Wed, 16 Dec 2020 21:59:17 +0000
Subject: Python 2 to Python 3 .so library incompatibility - need help
References: <aj1qah-olf.ln1@esprimo.zbmc.eu>
 <20201216212447.GA22531@cskk.homeip.net>
 <mailman.438.1608153893.7193.python-list@python.org>
Message-ID: <licqah-ri41.ln1@esprimo.zbmc.eu>

Cameron Simpson <cs at cskk.id.au> wrote:
> On 16Dec2020 18:51, Chris Green <cl at isbd.net> wrote:
> >The specific problem that finally prevented me from managing to get it
> >to work was a (Linux) .so file that had been built for Python 2 and,
> >as I don't have the source, I can't build for Python 3.
> 
> ChrisA I think suggested keeping a Python 2.7 install around for this.
> 
Not possible really as there are other python conflicts that start
appearing if one tries to retain the libraries needed.


> >I need to have another go at fixing this as otherwise the code that I
> >need to manage my printer will stop working as I update my Ubuntu
> >systems.
> 
> Have you considered keeping a legacy VM around as well? I have a few VMs 
> sitting here I use for some legacy software.
> 
That's not a lot of use.  The programs that I want to run (by
converting to Python 3) are utility programs for my printer, they
install with a handy 'app' in my toolbar.  Having them in a VM
wouldn't really do much good! :-)


> Have you checked an upgraded Ubuntu to failure to run your software 
> using Python 2? Python 2 won't be installed by default, but I'm pretty 
> sure you can add it in. It is just the "system Python" which is moving 
> to Python 3.
> 
> Also, make note of the specific Python 2 version where your software 
> works - the CPython API does change somewhat sometimes.
> 
I still have python 2.  The issue is that the programs need modules
which come from a PPA to support Python GTK, these conflict with
ongoing updates to Python.  The PPA works OK in Ubuntu 20.04 but
prevents some updates in 20.10.  I expect it will get worse as time
goes on.


> >The specific error I'm getting is as follows:-
> >    File "/usr/libexec/okimfputl.new/guicom.py", line 66, in <module> import pyscand
> >    ImportError: /usr/libexec/okimfpdrv/pyscand.so: undefined symbol: _Py_ZeroStruct
> 
> 
> Guessing from the library name, have you looked on the OKI.com site for 
> current software? Maybe here? What's your printer model?
> 
>     https://www.oki.com/au/printing/support/drivers-and-utilities/index.html
> 
> Not that I've found anything helpful...
> 
> What Ubuntu package supplies that .so file?
> 
It comes from OKI with the Linux utilities for the printer, it's an
MC342N.

I have tried asking them for a Python 3 version, maybe I should try
again.

-- 
Chris Green
?

From rosuav at gmail.com  Wed Dec 16 17:18:51 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 17 Dec 2020 09:18:51 +1100
Subject: Python 2 to Python 3 .so library incompatibility - need help
In-Reply-To: <licqah-ri41.ln1@esprimo.zbmc.eu>
References: <aj1qah-olf.ln1@esprimo.zbmc.eu>
 <20201216212447.GA22531@cskk.homeip.net>
 <mailman.438.1608153893.7193.python-list@python.org>
 <licqah-ri41.ln1@esprimo.zbmc.eu>
Message-ID: <CAPTjJmrR=XuVT3QCFoQ+gxWS+NZo7WS5ZZNVYHWqM40LzHgjDg@mail.gmail.com>

On Thu, Dec 17, 2020 at 9:06 AM Chris Green <cl at isbd.net> wrote:
> > Also, make note of the specific Python 2 version where your software
> > works - the CPython API does change somewhat sometimes.
> >
> I still have python 2.  The issue is that the programs need modules
> which come from a PPA to support Python GTK, these conflict with
> ongoing updates to Python.  The PPA works OK in Ubuntu 20.04 but
> prevents some updates in 20.10.  I expect it will get worse as time
> goes on.
>

Try getting JUST the printer info in Python 2, and then outputting
that to stdout in JSON format. Then your Python 3 script can run your
Python 2 script, read what it sends on stdout, and do whatever it
needs to.

ChrisA

From cs at cskk.id.au  Wed Dec 16 17:48:11 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Thu, 17 Dec 2020 09:48:11 +1100
Subject: Python 2 to Python 3 .so library incompatibility - need help
In-Reply-To: <licqah-ri41.ln1@esprimo.zbmc.eu>
References: <licqah-ri41.ln1@esprimo.zbmc.eu>
Message-ID: <20201216224811.GA63294@cskk.homeip.net>

On 16Dec2020 21:59, Chris Green <cl at isbd.net> wrote:
>Cameron Simpson <cs at cskk.id.au> wrote:
>> On 16Dec2020 18:51, Chris Green <cl at isbd.net> wrote:
>> >The specific problem that finally prevented me from managing to get it
>> >to work was a (Linux) .so file that had been built for Python 2 and,
>> >as I don't have the source, I can't build for Python 3.
>>
>> ChrisA I think suggested keeping a Python 2.7 install around for this.
>>
>Not possible really as there are other python conflicts that start
>appearing if one tries to retain the libraries needed.

Runtime python issues like you missing symbol error, or package conflict 
issues?

i.e. can you keep the OKI stuff sitting around along with Python 2 
install without having trouble with the PPA?

>> >I need to have another go at fixing this as otherwise the code that 
>> >I need to manage my printer will stop working as I update my Ubuntu
>> >systems.

I'm leaning towards ChrisA's JSON suggestion at this point (absent newer 
driver software). Keep a small Python 2 programme around which uses the 
printer driver in whatever _basic_ ways you need, and _invoke that_ from 
your modern Python 3 code as an external command, passing/receiving the 
necessary information in JSON form as input.output, or on its command 
line if that is more convenient.

>> Have you considered keeping a legacy VM around as well? I have a few VMs
>> sitting here I use for some legacy software.
>>
>That's not a lot of use.  The programs that I want to run (by
>converting to Python 3) are utility programs for my printer, they
>install with a handy 'app' in my toolbar.  Having them in a VM
>wouldn't really do much good! :-)

Fair enough. It seemed cumbersome to me too, but it is a viable way to 
keep something legacy around, particularly if that legacy thing requires 
a legacy OS.

>I still have python 2.  The issue is that the programs need modules
>which come from a PPA to support Python GTK, these conflict with
>ongoing updates to Python.  The PPA works OK in Ubuntu 20.04 but
>prevents some updates in 20.10.  I expect it will get worse as time
>goes on.
[...]
>> Guessing from the library name, have you looked on the OKI.com site 
>> for current software? Maybe here? What's your printer model?
>>     https://www.oki.com/au/printing/support/drivers-and-utilities/index.html
>>
>>
>It comes from OKI with the Linux utilities for the printer, it's an
>MC342N.

From here?

    https://www.oki.com/uk/printing/support/drivers-and-utilities/colour-multifunction/01331401/?os=ab33&lang=ac2

This driver?

    https://www.oki.com/uk/printing/support/drivers-and-utilities/?id=46252701FZ01&tab=drivers-and-utilities&productCategory=colour-multifunction&sku=01331401&os=ab33&lang=ac2

I've just installed the .deb above on my Ubuntu 20.04.1 LTS system.  
Aside from whinging about systemd it installed ok. How do I reproduce 
your problems? (I've got no printer of course, but...)

>I have tried asking them for a Python 3 version, maybe I should try
>again.

Can't hurt, but may not be necessary if you are prepared to split your 
Python 3 code form the Python 2 stuff that ships with the .deb.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From Bischoop at vimart.net  Wed Dec 16 21:33:56 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 02:33:56 -0000 (UTC)
Subject: Review, suggestion etc?
Message-ID: <slrnrtlgsk.drf.Bischoop@vimart.net>


I've done my biggest project that allowed me to learn a lot.
It's basically simply Database with basic options >> https://bpa.st/FU4A
.
What sucks here is basically the find_people() I'll have to work on it
yet to make it more useful.
.
If anyone was bored and wished to point me some wrong way or suggest a
better one I'd appreciate.

--
Thanks

From Bischoop at vimart.net  Wed Dec 16 21:40:51 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 02:40:51 -0000 (UTC)
Subject: Function returns old value
References: <slrnrt86vo.517.Bischoop@vimart.net> <rr185b$136c$1@ciao.gmane.io>
 <mailman.369.1607744941.7193.python-list@python.org>
Message-ID: <slrnrtlh9j.drf.Bischoop@vimart.net>

On 2020-12-12, Terry Reedy <tjreedy at udel.edu> wrote:
>
> Don't post links to unknown sites.  Reduce it to the minimum needed to 
> exhibit the questionable behavior and include inline with the question.
>
>> How this functions should look properly?
>
>

I've solved the problem.
BTW bpa.st/+python is well known for code sharing among Python
communities it's alternative to pastebin.com.

From PythonList at DancesWithMice.info  Wed Dec 16 21:56:16 2020
From: PythonList at DancesWithMice.info (dn)
Date: Thu, 17 Dec 2020 15:56:16 +1300
Subject: Function returns old value
In-Reply-To: <slrnrtlh9j.drf.Bischoop@vimart.net>
References: <slrnrt86vo.517.Bischoop@vimart.net> <rr185b$136c$1@ciao.gmane.io>
 <mailman.369.1607744941.7193.python-list@python.org>
 <slrnrtlh9j.drf.Bischoop@vimart.net>
Message-ID: <5b8a1f0b-07a1-6bc7-39d3-b441adbb2010@DancesWithMice.info>

On 17/12/2020 15:40, Bischoop wrote:
> On 2020-12-12, Terry Reedy <tjreedy at udel.edu> wrote:
>>
>> Don't post links to unknown sites.  Reduce it to the minimum needed to
>> exhibit the questionable behavior and include inline with the question.

> BTW bpa.st/+python is well known for code sharing among Python
> communities it's alternative to pastebin.com.


Remember that posts to the list are archived, and thus may be searched. 
People experiencing similar problems in-future will be able to 'mine' 
the archives for help and advice.

Using a/any pastebin is great for immediate sharing. Remember that in 
this case their links expire/the bin 'disappears'.

After expiry, any posts 'here' with links to 'there', will be useless.
-- 
Regards =dn

From Bischoop at vimart.net  Wed Dec 16 22:06:32 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 03:06:32 -0000 (UTC)
Subject: Function returns old value
References: <slrnrt86vo.517.Bischoop@vimart.net> <rr185b$136c$1@ciao.gmane.io>
 <mailman.369.1607744941.7193.python-list@python.org>
 <slrnrtlh9j.drf.Bischoop@vimart.net>
 <5b8a1f0b-07a1-6bc7-39d3-b441adbb2010@DancesWithMice.info>
 <mailman.442.1608173788.7193.python-list@python.org>
Message-ID: <slrnrtlipo.fgd.Bischoop@vimart.net>

On 2020-12-17, dn <PythonList at DancesWithMice.info> wrote:

> Remember that posts to the list are archived, and thus may be searched. 
> People experiencing similar problems in-future will be able to 'mine' 
> the archives for help and advice.
>
> Using a/any pastebin is great for immediate sharing. Remember that in 
> this case their links expire/the bin 'disappears'.
>
> After expiry, any posts 'here' with links to 'there', will be useless.

I do mind that however I thoght it better if paste a whole code to see
and pasting from my IDE to vim/slrn was messing syntax, I'll do better
next time.


From Bischoop at vimart.net  Wed Dec 16 21:48:39 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 02:48:39 -0000 (UTC)
Subject: Review, suggestion etc?
References: <slrnrtlgsk.drf.Bischoop@vimart.net>
Message-ID: <slrnrtlho7.drf.Bischoop@vimart.net>

On 2020-12-17, Bischoop <Bischoop at vimart.net> wrote:


Accidently removed the paste, https://bpa.st/E3FQ

From PythonList at DancesWithMice.info  Wed Dec 16 22:22:53 2020
From: PythonList at DancesWithMice.info (dn)
Date: Thu, 17 Dec 2020 16:22:53 +1300
Subject: Function returns old value
In-Reply-To: <slrnrtlipo.fgd.Bischoop@vimart.net>
References: <slrnrt86vo.517.Bischoop@vimart.net> <rr185b$136c$1@ciao.gmane.io>
 <mailman.369.1607744941.7193.python-list@python.org>
 <slrnrtlh9j.drf.Bischoop@vimart.net>
 <5b8a1f0b-07a1-6bc7-39d3-b441adbb2010@DancesWithMice.info>
 <mailman.442.1608173788.7193.python-list@python.org>
 <slrnrtlipo.fgd.Bischoop@vimart.net>
Message-ID: <6c4028ef-0359-098e-6066-87765d51fb6a@DancesWithMice.info>

On 17/12/2020 16:06, Bischoop wrote:
> On 2020-12-17, dn <PythonList at DancesWithMice.info> wrote:
> 
>> Remember that posts to the list are archived, and thus may be searched.
>> People experiencing similar problems in-future will be able to 'mine'
>> the archives for help and advice.
>>
>> Using a/any pastebin is great for immediate sharing. Remember that in
>> this case their links expire/the bin 'disappears'.
>>
>> After expiry, any posts 'here' with links to 'there', will be useless.
> 
> I do mind that however I thoght it better if paste a whole code to see
> and pasting from my IDE to vim/slrn was messing syntax, I'll do better
> next time.


Yes, it can be difficult to know how much code to include and how much 
can be left-out. Don't worry about that - replies can always trim any 
excess.

Also, don't be concerned about such comments. Rather than complaints, 
please regard them as advice from folk who have been 'here' and/or using 
Python for some time.
-- 
Regards =dn

From greg.ewing at canterbury.ac.nz  Thu Dec 17 04:44:27 2020
From: greg.ewing at canterbury.ac.nz (Greg Ewing)
Date: Thu, 17 Dec 2020 22:44:27 +1300
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <mailman.434.1608147246.7193.python-list@python.org>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com> <rrb0ug$88n$1@ciao.gmane.io>
 <1823740026.830499.1608062933098@mail.yahoo.com>
 <t0hktf5lcbm4k3fjfj5na5tnvp2k87kdpj@4ax.com> <rrdnab$361$1@ciao.gmane.io>
 <mailman.434.1608147246.7193.python-list@python.org>
Message-ID: <i40njrF6okeU1@mid.individual.net>

On 17/12/20 8:31 am, Grant Edwards wrote:
> On 2020-12-16, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
>> https://en.wikipedia.org/wiki/Evaluation_strategy#Call_by_name
> 
> I vaguely recall some other old
> language I ran across in a survey course when in college that used it.
> IIRC it was Algol.

Algol 60.

Also, Lisp macros effectively let you do something similar.

-- 
Greg

From hjp-python at hjp.at  Thu Dec 17 04:57:51 2020
From: hjp-python at hjp.at (Peter J. Holzer)
Date: Thu, 17 Dec 2020 10:57:51 +0100
Subject: Function returns old value
In-Reply-To: <slrnrtlipo.fgd.Bischoop@vimart.net>
References: <slrnrt86vo.517.Bischoop@vimart.net> <rr185b$136c$1@ciao.gmane.io>
 <mailman.369.1607744941.7193.python-list@python.org>
 <slrnrtlh9j.drf.Bischoop@vimart.net>
 <5b8a1f0b-07a1-6bc7-39d3-b441adbb2010@DancesWithMice.info>
 <mailman.442.1608173788.7193.python-list@python.org>
 <slrnrtlipo.fgd.Bischoop@vimart.net>
Message-ID: <20201217095751.GA8064@hjp.at>

On 2020-12-17 03:06:32 -0000, Bischoop wrote:
> pasting from my IDE to vim/slrn was messing syntax,

You can 

:set paste

in vim to prevent it from messing with pasted content (don't forget to
set nopaste afterwards).

With newer vims that's rarely necessary though since they can distinguish
between input that was pasted and input that was typed.

        hp

-- 
   _  | Peter J. Holzer    | Story must make more sense than reality.
|_|_) |                    |
| |   | hjp at hjp.at         |    -- Charles Stross, "Creative writing
__/   | http://www.hjp.at/ |       challenge!"
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From cl at isbd.net  Thu Dec 17 04:58:24 2020
From: cl at isbd.net (Chris Green)
Date: Thu, 17 Dec 2020 09:58:24 +0000
Subject: Python 2 to Python 3 .so library incompatibility - need help
References: <licqah-ri41.ln1@esprimo.zbmc.eu>
 <20201216224811.GA63294@cskk.homeip.net>
 <mailman.441.1608158902.7193.python-list@python.org>
Message-ID: <0nmrah-odo3.ln1@esprimo.zbmc.eu>

Cameron Simpson <cs at cskk.id.au> wrote:
> >> Guessing from the library name, have you looked on the OKI.com site 
> >> for current software? Maybe here? What's your printer model?
> >>     https://www.oki.com/au/printing/support/drivers-and-utilities/index.html
> >>
> >>
> >It comes from OKI with the Linux utilities for the printer, it's an
> >MC342N.
> 
> From here?
> 
> https://www.oki.com/uk/printing/support/drivers-and-utilities/colour-multifunction/01331401/?os=ab33&lang=ac2 
> 
> 
> This driver?
> 
> https://www.oki.com/uk/printing/support/drivers-and-utilities/?id=46252701FZ01&tab=drivers-and-utilities&productCategory=colour-multifunction&sku=01331401&os=ab33&lang=ac2 
> 
> 
> I've just installed the .deb above on my Ubuntu 20.04.1 LTS system.  
> Aside from whinging about systemd it installed ok. How do I reproduce 
> your problems? (I've got no printer of course, but...)
> 
Try running scantool.py, that should pop up a little GUI.

It uses GTK which of course in itself makes migration tricky because
one has to move from the native Python 2 code to the 'introspection'
code on Python 3.  However I can do those code changes, the killer is
that several of the scripts import pyscand and that's the Python 2
library.

The issue basically is that you can't run Python 2 GTK in a modern
system that's mostly Python 3 because the GTK libraries conflict. Thus
I need to convert the code to Python 3 but I can't because of the
library.

I've extracted all the calls/uses of pyscand from the Python code:-

    pyscand.ADF:
    pyscand.BEGIN:
    pyscand.EVENT_PUSHSCAN:
    pyscand.EVENT_PUSHSCANCCL:
    pyscand.E_BUSY
    pyscand.E_BUSY:
    pyscand.E_CANCELED:
    pyscand.E_CONNECTION_REFUSED:
    pyscand.E_ERROR
    pyscand.E_IOERROR:
    pyscand.E_NODATA:
    pyscand.E_SUCCESS
    pyscand.E_SUCCESS:
    pyscand.FINISHED:
    pyscand.O_HEIGHT
    pyscand.O_PAPER_HEIGHT
    pyscand.O_PAPER_WIDTH
    pyscand.O_WIDTH
    pyscand.PRM_ACTION
    pyscand.PRM_DEVICE
    pyscand.PRM_DEVICE
    pyscand.PRM_PAGE
    pyscand.PRM_PATH
    pyscand.PRM_PROGRESS
    pyscand.PRM_PUSHSCAN_ID
    pyscand.PRM_SOURCE
    pyscand.PRM_STATUS
    pyscand.PROGRESS:
    pyscand.TO_APPLICATION:
    pyscand.TO_FOLDER:
    pyscand.cancel_register_client()
    pyscand.cancel_scan(device)
    pyscand.exit_client()
    pyscand.get_device_list(devicelist)
    pyscand.is_registered()
    pyscand.recv_client_event()
    pyscand.register_client()
    pyscand.scan(self._device, self._cfg, outpath, self._scan_callback,
    self._pushscanid)
    pyscand.strstatus(rc)))
    pyscand.strstatus(status)
    pyscandsupp.to_device_name_list(devicelist)

As you can see it's mostly constants but there's that pyscand.scan()
at the bottom which I suspect is the fundamental scanning software.

-- 
Chris Green
?

From swistakm at gmail.com  Thu Dec 17 04:51:50 2020
From: swistakm at gmail.com (=?UTF-8?Q?Micha=C5=82_Jaworski?=)
Date: Thu, 17 Dec 2020 10:51:50 +0100
Subject: Python 2 to Python 3 .so library incompatibility - need help
In-Reply-To: <20201216224811.GA63294@cskk.homeip.net>
References: <licqah-ri41.ln1@esprimo.zbmc.eu>
 <20201216224811.GA63294@cskk.homeip.net>
Message-ID: <CAMkRj3GJxBGprscXpkRrJ8OjYMsFc43kTn=Qv+67bdm3OYemfw@mail.gmail.com>

I've looked into the details of the deb package that Cameron mentioned. It
may be the one that you Chris uss because it does indeed include a
pyscand.so file. Quick question to you Chris: the utilities
you've mentioned are the code that you've written yourself or utilities
from /usr/libexec/okimfputl that are shipped with the "driver package". In
the deb package I've found following files:
/usr/libexec/okimfputl/imgfilecv.py
/usr/libexec/okimfputl/pushconfig.py
/usr/libexec/okimfputl/pushass.py
/usr/libexec/okimfputl/mfpcfgfile.py
...

If that's the latter, I wouldn't even try to port that to Python 3. First,
it would be clearly against the licence agreement. Second, that would
probably result in total mess and take more time that it takes to earn for
a new printer. If you really want to keep the printer (I wouldn't) I would
do the following: upgrade your system, install Python 2.7 straight from
sources in a separate location (e.g. /opt/oki-python?) and modify all
shebang lines of the OKI python utilities from utilities to use that python
location instead of "/usr/bin/env python" or "/usr/bin/python". That would
make it totally independent of your system installation. The last thing
would be probably installing pygtk in that "isolated" python installation
as OKI utilities clearly rely on this. You could use venv for that or just
simply make sure that gtk for python2 is in that python's library path.
Whatever more convenient: you won't be using that python installation for
anything else than supporting the driver.

To be honest, what I would really do is to buy a new printer from a vendor
that is known to be supporting their hardware for long term on the system
you use. Printer vendors sucks. In the end, they always stop producing
printing supplies you need and render your hardware useless. I have a combo
that I can't refill with toner anymore which has used photoconductor drum
that I can't replace anymore. I keep it around because it has a working
scanner and haven't buyed a new printer because this one "almost works".

Cheers,
Micha?

?r., 16 gru 2020 o 23:48 Cameron Simpson <cs at cskk.id.au> napisa?(a):

> On 16Dec2020 21:59, Chris Green <cl at isbd.net> wrote:
> >Cameron Simpson <cs at cskk.id.au> wrote:
> >> On 16Dec2020 18:51, Chris Green <cl at isbd.net> wrote:
> >> >The specific problem that finally prevented me from managing to get it
> >> >to work was a (Linux) .so file that had been built for Python 2 and,
> >> >as I don't have the source, I can't build for Python 3.
> >>
> >> ChrisA I think suggested keeping a Python 2.7 install around for this.
> >>
> >Not possible really as there are other python conflicts that start
> >appearing if one tries to retain the libraries needed.
>
> Runtime python issues like you missing symbol error, or package conflict
> issues?
>
> i.e. can you keep the OKI stuff sitting around along with Python 2
> install without having trouble with the PPA?
>
> >> >I need to have another go at fixing this as otherwise the code that
> >> >I need to manage my printer will stop working as I update my Ubuntu
> >> >systems.
>
> I'm leaning towards ChrisA's JSON suggestion at this point (absent newer
> driver software). Keep a small Python 2 programme around which uses the
> printer driver in whatever _basic_ ways you need, and _invoke that_ from
> your modern Python 3 code as an external command, passing/receiving the
> necessary information in JSON form as input.output, or on its command
> line if that is more convenient.
>
> >> Have you considered keeping a legacy VM around as well? I have a few VMs
> >> sitting here I use for some legacy software.
> >>
> >That's not a lot of use.  The programs that I want to run (by
> >converting to Python 3) are utility programs for my printer, they
> >install with a handy 'app' in my toolbar.  Having them in a VM
> >wouldn't really do much good! :-)
>
> Fair enough. It seemed cumbersome to me too, but it is a viable way to
> keep something legacy around, particularly if that legacy thing requires
> a legacy OS.
>
> >I still have python 2.  The issue is that the programs need modules
> >which come from a PPA to support Python GTK, these conflict with
> >ongoing updates to Python.  The PPA works OK in Ubuntu 20.04 but
> >prevents some updates in 20.10.  I expect it will get worse as time
> >goes on.
> [...]
> >> Guessing from the library name, have you looked on the OKI.com site
> >> for current software? Maybe here? What's your printer model?
> >>
> https://www.oki.com/au/printing/support/drivers-and-utilities/index.html
> >>
> >>
> >It comes from OKI with the Linux utilities for the printer, it's an
> >MC342N.
>
> From here?
>
>
> https://www.oki.com/uk/printing/support/drivers-and-utilities/colour-multifunction/01331401/?os=ab33&lang=ac2
>
> This driver?
>
>
> https://www.oki.com/uk/printing/support/drivers-and-utilities/?id=46252701FZ01&tab=drivers-and-utilities&productCategory=colour-multifunction&sku=01331401&os=ab33&lang=ac2
>
> I've just installed the .deb above on my Ubuntu 20.04.1 LTS system.
> Aside from whinging about systemd it installed ok. How do I reproduce
> your problems? (I've got no printer of course, but...)
>
> >I have tried asking them for a Python 3 version, maybe I should try
> >again.
>
> Can't hurt, but may not be necessary if you are prepared to split your
> Python 3 code form the Python 2 stuff that ships with the .deb.
>
> Cheers,
> Cameron Simpson <cs at cskk.id.au>
> --
> https://mail.python.org/mailman/listinfo/python-list
>

From patatetom at gmail.com  Thu Dec 17 05:17:37 2020
From: patatetom at gmail.com (Pascal)
Date: Thu, 17 Dec 2020 11:17:37 +0100
Subject: sudo python PermissionError [Errno 13] Permission denied
Message-ID: <CAGhAaddW0swEaRPSO4TWts--P6LoysKgWv7DF9pOFLyg1T6=0w@mail.gmail.com>

hi,

here, I have this simple script that tests if the /tmp/test file can be
opened in write mode :

$ cat /tmp/append
#!/usr/bin/python
with open('/tmp/test', 'a'): pass

the file does not exist yet :

$ chmod +x /tmp/append
$ ls -l /tmp/test
ls: cannot access '/tmp/test': No such file or directory

the script is launched as a simple user :

$ /tmp/append
$ ls -l /tmp/test
-rw-r--r-- 1 user user 0 Dec 17 10:30 /tmp/test

everything is ok.
now, the script fails if it is replayed as root user with the sudo command :

$ sudo /tmp/append
[sudo] password for user:
Traceback (most recent call last):
  File "/tmp/append", line 2, in <module>
    with open('/tmp/test', 'a'):
PermissionError: [Errno 13] Permission denied: '/tmp/test'

the problem is the same if the opening mode is 'w' or if "sudo -i" or "su -"
are used.

why can't root user under python manipulate the simple user file ?

regards, lacsaP.

From nospam at please.ty  Thu Dec 17 06:16:29 2020
From: nospam at please.ty (jak)
Date: Thu, 17 Dec 2020 12:16:29 +0100
Subject: dict.get(key, default) evaluates default even if key exists
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <mailman.397.1608055014.7193.python-list@python.org>
Message-ID: <rrfemc$v72$1@gioia.aioe.org>

Il 15/12/2020 18:07, Mark Polesky ha scritto:
> Hi.
> 
> # Running this script....
> 
> D = {'a':1}
> def get_default():
>  ??? print('Nobody expects this')
>  ??? return 0
> print(D.get('a', get_default()))
> 
> # ...generates this output:
> 
> Nobody expects this
> 1
> 
> ###
> 
> Since I'm brand new to this community, I thought I'd ask here first... Is this worthy of a bug report?? This behavior is definitely unexpected to me, and I accidentally coded an endless loop in a mutual recursion situation because of it.? Calling dict.get.__doc__ only gives this short sentence: Return the value for key if key is in the dictionary, else default.? Nothing in that docstring suggests that the default value is evaluated even if the key exists, and I can't think of any good reason to do so.
> 
> Am I missing something?
> 
> Thanks,
> Mark
> 

print(_ if d.get('a', None) is not None else get_default())




From nospam at please.ty  Thu Dec 17 06:32:39 2020
From: nospam at please.ty (jak)
Date: Thu, 17 Dec 2020 12:32:39 +0100
Subject: dict.get(key, default) evaluates default even if key exists
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <mailman.397.1608055014.7193.python-list@python.org>
 <rrfemc$v72$1@gioia.aioe.org>
Message-ID: <rrffkl$1dpo$1@gioia.aioe.org>

Il 17/12/2020 12:16, jak ha scritto:
> Il 15/12/2020 18:07, Mark Polesky ha scritto:
>> Hi.
>>
>> # Running this script....
>>
>> D = {'a':1}
>> def get_default():
>> ???? print('Nobody expects this')
>> ???? return 0
>> print(D.get('a', get_default()))
>>
>> # ...generates this output:
>>
>> Nobody expects this
>> 1
>>
>> ###
>>
>> Since I'm brand new to this community, I thought I'd ask here first... 
>> Is this worthy of a bug report?? This behavior is definitely 
>> unexpected to me, and I accidentally coded an endless loop in a mutual 
>> recursion situation because of it.? Calling dict.get.__doc__ only 
>> gives this short sentence: Return the value for key if key is in the 
>> dictionary, else default.? Nothing in that docstring suggests that the 
>> default value is evaluated even if the key exists, and I can't think 
>> of any good reason to do so.
>>
>> Am I missing something?
>>
>> Thanks,
>> Mark
>>
> 
> print(_ if d.get('a', None) is not None else get_default())
> 
> 
> 
ops...

print((_ if d.get('a', None) is not None else get_default()))


From hjp-python at hjp.at  Thu Dec 17 06:40:49 2020
From: hjp-python at hjp.at (Peter J. Holzer)
Date: Thu, 17 Dec 2020 12:40:49 +0100
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <rrfemc$v72$1@gioia.aioe.org>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <mailman.397.1608055014.7193.python-list@python.org>
 <rrfemc$v72$1@gioia.aioe.org>
Message-ID: <20201217114049.GB8064@hjp.at>

On 2020-12-17 12:16:29 +0100, jak wrote:
> print(_ if d.get('a', None) is not None else get_default())

That doesn't work:

>>> print(_ if d.get('a', None) is not None else get_default())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name '_' is not defined

But this works:

>>> print(_ if (_ := d.get('a', None)) is not None else get_default())
1

(I would prefer ChrisA's solution, though.)

        hp

-- 
   _  | Peter J. Holzer    | Story must make more sense than reality.
|_|_) |                    |
| |   | hjp at hjp.at         |    -- Charles Stross, "Creative writing
__/   | http://www.hjp.at/ |       challenge!"
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From swistakm at gmail.com  Thu Dec 17 06:55:31 2020
From: swistakm at gmail.com (=?UTF-8?Q?Micha=C5=82_Jaworski?=)
Date: Thu, 17 Dec 2020 12:55:31 +0100
Subject: Review, suggestion etc?
In-Reply-To: <slrnrtlho7.drf.Bischoop@vimart.net>
References: <slrnrtlgsk.drf.Bischoop@vimart.net>
 <slrnrtlho7.drf.Bischoop@vimart.net>
Message-ID: <CAMkRj3GqXyFxEeRZUACYgrJ56B2JvKGfV+dRGd8EhnmOzCZBpg@mail.gmail.com>

I've made a quick look at the code and even executed it. It looks pretty
clear and is easy to understand, although it has some structural problems.
I won't do a thorough review but highlight the most important problems.

First, the recursive user input pattern you use:
      def marriage():
        maritals = input('Married: Yes/No ?: ').title()
        while maritals != 'Yes' and maritals != 'No':
            return marriage()
        return maritals

It may look really convenient but you should really avoid that. In small
amounts it can be harmless, but it is kind of a resource leak. Aslo this
pattern is omnipresent so can quickly get out of hand and exceed maximum
recursion depth:

   ...
   You can choose only numbers.
   What you wanna do?:
   You can choose only numbers.
   What you wanna do?:
   You can choose only numbers.
   What you wanna do?:
   You can choose only numbers.
   What you wanna do?:
   You can choose only numbers.
   What you wanna do?:
   You can choose only numbers.
   Fatal Python error: Cannot recover from stack overflow.

   Current thread 0x0000000112836dc0 (most recent call first):
     ...
     File "vimart.py", line 52 in menu_choice
     File "vimart.py", line 52 in menu_choice
     ...
   Abort trap: 6

Also, this choice-prompt pattern could be moved to a separate general
function so you don't have to repeat it all over the code. Take a look at
the prompt() function from click.termui module to get a better
understanding on how to build such things (
https://github.com/pallets/click/blob/master/src/click/termui.py). I would
also recommend creating helper functions for common things like displaying
results because right now it's hard to figure out which parts of
application constitute its presentation layer and which are part of "core
logic". Try to keep these two concepts separate and you will get better
results.

Second major structural "problem" are inline function definitions:

def add_people():
    def how_old():
        ...

    def p_sex():
        ...

    def marriage():
        ...

You shouldn't be doing that unless you need a closure with nonlocal
variables to read from. Otherwise it really harms the readability. I
understand the urge to keep relevant code close to the usage but you would
have better results with modules. If you really want to keep everything in
a single module, keep functions close together in the file but don't nest
them. Use relevant naming conventions instead. Simply think of how you
would write that in C. You could use some object-oriented approach too, but
I would recommend polishing structural programming first.

There are also other issues like not always closing files, and not
validating the user input in specific places. Still, these will be more
evident as you improve the structure of application and do thorough
testing. Anyway, the code doesn't look bad. It of course needs improvement
but I've also seen worse specimens from people being actually paid for
writing the code.

Remember that "how to make things better" is a function of few parameters:
- what you want to achieve
- what are you able to do
- how much time do you have

If your sole goal is to learn and improve skills, I would recommend
polishing this in current procedural fashion to some extent, but not trying
to make it perfect. Then I would start from scratch and experiment with
different paradigms (OOP for instance). Then I would try to make a smaller
project that has some actual utility.

czw., 17 gru 2020 o 04:17 Bischoop <Bischoop at vimart.net> napisa?(a):

> On 2020-12-17, Bischoop <Bischoop at vimart.net> wrote:
>
>
> Accidently removed the paste, https://bpa.st/E3FQ
> --
> https://mail.python.org/mailman/listinfo/python-list
>

From 2QdxY4RzWzUUiLuE at potatochowder.com  Thu Dec 17 07:06:22 2020
From: 2QdxY4RzWzUUiLuE at potatochowder.com (2QdxY4RzWzUUiLuE at potatochowder.com)
Date: Thu, 17 Dec 2020 06:06:22 -0600
Subject: sudo python PermissionError [Errno 13] Permission denied
In-Reply-To: <CAGhAaddW0swEaRPSO4TWts--P6LoysKgWv7DF9pOFLyg1T6=0w@mail.gmail.com>
References: <CAGhAaddW0swEaRPSO4TWts--P6LoysKgWv7DF9pOFLyg1T6=0w@mail.gmail.com>
Message-ID: <X9tJviXLNtXegO8x@scrozzle>

On 2020-12-17 at 11:17:37 +0100,
Pascal <patatetom at gmail.com> wrote:

> hi,
> 
> here, I have this simple script that tests if the /tmp/test file can be
> opened in write mode :
> 
> $ cat /tmp/append
> #!/usr/bin/python
> with open('/tmp/test', 'a'): pass
> 
> the file does not exist yet :
> 
> $ chmod +x /tmp/append
> $ ls -l /tmp/test
> ls: cannot access '/tmp/test': No such file or directory
> 
> the script is launched as a simple user :
> 
> $ /tmp/append
> $ ls -l /tmp/test
> -rw-r--r-- 1 user user 0 Dec 17 10:30 /tmp/test
> 
> everything is ok.
> now, the script fails if it is replayed as root user with the sudo command :
> 
> $ sudo /tmp/append
> [sudo] password for user:
> Traceback (most recent call last):
>   File "/tmp/append", line 2, in <module>
>     with open('/tmp/test', 'a'):
> PermissionError: [Errno 13] Permission denied: '/tmp/test'
> 
> the problem is the same if the opening mode is 'w' or if "sudo -i" or "su -"
> are used.
> 
> why can't root user under python manipulate the simple user file ?

This has to do with the idiosyncratic permissions of the /tmp directory
and not your code.  In my shell on my Linux box:

    $ rm -f /tmp/x
    $ echo x >/tmp/x
    $ echo x | sudo tee /tmp/x
    tee: /tmp/x: Permission denied
    x

    $ ls -ld /tmp
    drwxrwxrwt 13 root root 380 Dec 17 06:03 /tmp

Try your experiment in a different directory, one without the sticky bit
set.

From nospam at please.ty  Thu Dec 17 07:10:17 2020
From: nospam at please.ty (jak)
Date: Thu, 17 Dec 2020 13:10:17 +0100
Subject: dict.get(key, default) evaluates default even if key exists
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <mailman.397.1608055014.7193.python-list@python.org>
 <rrfemc$v72$1@gioia.aioe.org> <20201217114049.GB8064@hjp.at>
 <mailman.447.1608205256.7193.python-list@python.org>
Message-ID: <rrfhr7$fmh$1@gioia.aioe.org>

Il 17/12/2020 12:40, Peter J. Holzer ha scritto:
> On 2020-12-17 12:16:29 +0100, jak wrote:
>> print(_ if d.get('a', None) is not None else get_default())
> 
> That doesn't work:
> 
>>>> print(_ if d.get('a', None) is not None else get_default())
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
> NameError: name '_' is not defined
> 
> But this works:
> 
>>>> print(_ if (_ := d.get('a', None)) is not None else get_default())
> 1
> 
> (I would prefer ChrisA's solution, though.)
> 
>          hp
> 
this one?

""""

D['a'] if 'a' in D else get_default()

ChrisA

""""

This solution search two times same key.

From rosuav at gmail.com  Thu Dec 17 07:33:55 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 17 Dec 2020 23:33:55 +1100
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <rrfhr7$fmh$1@gioia.aioe.org>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <mailman.397.1608055014.7193.python-list@python.org>
 <rrfemc$v72$1@gioia.aioe.org> <20201217114049.GB8064@hjp.at>
 <mailman.447.1608205256.7193.python-list@python.org>
 <rrfhr7$fmh$1@gioia.aioe.org>
Message-ID: <CAPTjJmoMWFLfUEbK43WQcBNmLsA5yUXxFa85vt-eKXhVkx2_SQ@mail.gmail.com>

On Thu, Dec 17, 2020 at 11:16 PM jak <nospam at please.ty> wrote:
>
> Il 17/12/2020 12:40, Peter J. Holzer ha scritto:
> > On 2020-12-17 12:16:29 +0100, jak wrote:
> >> print(_ if d.get('a', None) is not None else get_default())
> >
> > That doesn't work:
> >
> >>>> print(_ if d.get('a', None) is not None else get_default())
> > Traceback (most recent call last):
> >    File "<stdin>", line 1, in <module>
> > NameError: name '_' is not defined
> >
> > But this works:
> >
> >>>> print(_ if (_ := d.get('a', None)) is not None else get_default())
> > 1
> >
> > (I would prefer ChrisA's solution, though.)
> >
> >          hp
> >
> this one?
>
> """"
>
> D['a'] if 'a' in D else get_default()
>
> ChrisA
>
> """"
>
> This solution search two times same key.

Yes, it does, but hash lookups are pretty fast. Unless your key is
some sort of custom object with a very expensive __hash__ function,
the double lookup isn't going to be too costly. But if that does
bother you, you can write it as a try/except instead.

ChrisA

From nospam at please.ty  Thu Dec 17 07:36:03 2020
From: nospam at please.ty (jak)
Date: Thu, 17 Dec 2020 13:36:03 +0100
Subject: dict.get(key, default) evaluates default even if key exists
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <mailman.397.1608055014.7193.python-list@python.org>
 <rrfemc$v72$1@gioia.aioe.org> <20201217114049.GB8064@hjp.at>
 <mailman.447.1608205256.7193.python-list@python.org>
Message-ID: <rrfjbh$16n0$1@gioia.aioe.org>

Il 17/12/2020 12:40, Peter J. Holzer ha scritto:
> On 2020-12-17 12:16:29 +0100, jak wrote:
>> print(_ if d.get('a', None) is not None else get_default())
> 
> That doesn't work:
> 
>>>> print(_ if d.get('a', None) is not None else get_default())
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
> NameError: name '_' is not defined
> 
> But this works:
> 
>>>> print(_ if (_ := d.get('a', None)) is not None else get_default())
> 1
> 
> (I would prefer ChrisA's solution, though.)
> 
>          hp
> 

I had already corrected my oversight (jak 12:32):

 > print((_ if d.get('a', None) is not None else get_default()))

while your fix works but not correctly because in that way does not 
collect the return code of the function get_default().

From patatetom at gmail.com  Thu Dec 17 07:43:42 2020
From: patatetom at gmail.com (Pascal)
Date: Thu, 17 Dec 2020 13:43:42 +0100
Subject: sudo python PermissionError [Errno 13] Permission denied
In-Reply-To: <X9tJviXLNtXegO8x@scrozzle>
References: <CAGhAaddW0swEaRPSO4TWts--P6LoysKgWv7DF9pOFLyg1T6=0w@mail.gmail.com>
 <X9tJviXLNtXegO8x@scrozzle>
Message-ID: <CAGhAadcHh--eVZ5ZOg5_OtVw737nAKcx8F9uFf741egqYkQ_Dw@mail.gmail.com>

you are right !

the "sticky bit" set to /tmp/ prevents the root user from altering the file
belonging to the simple user !

$ ls -ld /tmp/
drwxrwxrwt 13 root root 320 Dec 17 13:22 /tmp/

$ ls -l /tmp/test
-rw-r--r-- 1 user 0 Dec 17 13:24 /tmp/test

$ echo test | sudo tee -a /tmp/test
tee: /tmp/test: Permission denied
test

but it does not prevent its deletion !

$ sudo rm -v /tmp/test
removed '/tmp/test'.

which misled me : sorry for the waste of time.

happy end of year 2020, lacsaP.

Le jeu. 17 d?c. 2020 ? 13:09, <2QdxY4RzWzUUiLuE at potatochowder.com> a ?crit :

> On 2020-12-17 at 11:17:37 +0100,
> Pascal <patatetom at gmail.com> wrote:
>
> > hi,
> >
> > here, I have this simple script that tests if the /tmp/test file can be
> > opened in write mode :
> >
> > $ cat /tmp/append
> > #!/usr/bin/python
> > with open('/tmp/test', 'a'): pass
> >
> > the file does not exist yet :
> >
> > $ chmod +x /tmp/append
> > $ ls -l /tmp/test
> > ls: cannot access '/tmp/test': No such file or directory
> >
> > the script is launched as a simple user :
> >
> > $ /tmp/append
> > $ ls -l /tmp/test
> > -rw-r--r-- 1 user user 0 Dec 17 10:30 /tmp/test
> >
> > everything is ok.
> > now, the script fails if it is replayed as root user with the sudo
> command :
> >
> > $ sudo /tmp/append
> > [sudo] password for user:
> > Traceback (most recent call last):
> >   File "/tmp/append", line 2, in <module>
> >     with open('/tmp/test', 'a'):
> > PermissionError: [Errno 13] Permission denied: '/tmp/test'
> >
> > the problem is the same if the opening mode is 'w' or if "sudo -i" or
> "su -"
> > are used.
> >
> > why can't root user under python manipulate the simple user file ?
>
> This has to do with the idiosyncratic permissions of the /tmp directory
> and not your code.  In my shell on my Linux box:
>
>     $ rm -f /tmp/x
>     $ echo x >/tmp/x
>     $ echo x | sudo tee /tmp/x
>     tee: /tmp/x: Permission denied
>     x
>
>     $ ls -ld /tmp
>     drwxrwxrwt 13 root root 380 Dec 17 06:03 /tmp
>
> Try your experiment in a different directory, one without the sticky bit
> set.
> --
> https://mail.python.org/mailman/listinfo/python-list
>

From nospam at please.ty  Thu Dec 17 07:49:22 2020
From: nospam at please.ty (jak)
Date: Thu, 17 Dec 2020 13:49:22 +0100
Subject: dict.get(key, default) evaluates default even if key exists
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
 <mailman.397.1608055014.7193.python-list@python.org>
 <rrfemc$v72$1@gioia.aioe.org> <20201217114049.GB8064@hjp.at>
 <mailman.447.1608205256.7193.python-list@python.org>
 <rrfhr7$fmh$1@gioia.aioe.org>
 <CAPTjJmoMWFLfUEbK43WQcBNmLsA5yUXxFa85vt-eKXhVkx2_SQ@mail.gmail.com>
 <mailman.450.1608208448.7193.python-list@python.org>
Message-ID: <rrfk4g$1isj$1@gioia.aioe.org>

Il 17/12/2020 13:33, Chris Angelico ha scritto:
> On Thu, Dec 17, 2020 at 11:16 PM jak <nospam at please.ty> wrote:
>>
>> Il 17/12/2020 12:40, Peter J. Holzer ha scritto:
>>> On 2020-12-17 12:16:29 +0100, jak wrote:
>>>> print(_ if d.get('a', None) is not None else get_default())
>>>
>>> That doesn't work:
>>>
>>>>>> print(_ if d.get('a', None) is not None else get_default())
>>> Traceback (most recent call last):
>>>     File "<stdin>", line 1, in <module>
>>> NameError: name '_' is not defined
>>>
>>> But this works:
>>>
>>>>>> print(_ if (_ := d.get('a', None)) is not None else get_default())
>>> 1
>>>
>>> (I would prefer ChrisA's solution, though.)
>>>
>>>           hp
>>>
>> this one?
>>
>> """"
>>
>> D['a'] if 'a' in D else get_default()
>>
>> ChrisA
>>
>> """"
>>
>> This solution search two times same key.
> 
> Yes, it does, but hash lookups are pretty fast. Unless your key is
> some sort of custom object with a very expensive __hash__ function,
> the double lookup isn't going to be too costly. But if that does
> bother you, you can write it as a try/except instead.
> 
> ChrisA
> 

try/except is a very expensive time. if we have a small dictionary in 
which you do little research, you definitely have reason. I would be 
curious to see the differences by taking times with 50 / 60K records by 
repeating the search 1 or 2 million times with and without try/except 
and also searching 1 or 2 times too.

Cheers

From Bischoop at vimart.net  Thu Dec 17 11:10:44 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 16:10:44 -0000 (UTC)
Subject: Review, suggestion etc?
References: <slrnrtlgsk.drf.Bischoop@vimart.net>
 <slrnrtlho7.drf.Bischoop@vimart.net>
 <CAMkRj3GqXyFxEeRZUACYgrJ56B2JvKGfV+dRGd8EhnmOzCZBpg@mail.gmail.com>
 <mailman.448.1608206143.7193.python-list@python.org>
Message-ID: <slrnrtn0o4.54o.Bischoop@vimart.net>

On 2020-12-17, Micha? Jaworski <swistakm at gmail.com> wrote:

Thanks for feedback and useful tips. 
I couldn't use any OOP here because have not a clue about it, just going
to go toward it.


> I've made a quick look at the code and even executed it. It looks pretty
> clear and is easy to understand, although it has some structural problems.
> I won't do a thorough review but highlight the most important problems.
>
> First, the recursive user input pattern you use:
>       def marriage():
>         maritals = input('Married: Yes/No ?: ').title()
>         while maritals != 'Yes' and maritals != 'No':
>             return marriage()
>         return maritals
>
>
>     def marriage():
>         ...
>

Could you expand here, I rather don't know how I could do it different
way apart from if maritals == 'Yes' or maritals == 'No' or is it what
you meant?


> You shouldn't be doing that unless you need a closure with nonlocal
> variables to read from. Otherwise it really harms the readability. I
> understand the urge to keep relevant code close to the usage but you would
> have better results with modules. If you really want to keep everything in
> a single module, keep functions close together in the file but don't nest
> them. Use relevant naming conventions instead. Simply think of how you
> would write that in C. You could use some object-oriented approach too, but
> I would recommend polishing structural programming first.
>

Well I don't know C, the only other language I was learning it was basic
for Atari :-) So in other words I shoudn't nest functions like in
changes(), add_people() etc but keep
everything in one functions. 

> There are also other issues like not always closing files, and not
> validating the user input in specific places. Still, these will be more
> evident as you improve the structure of application and do thorough
> testing. Anyway, the code doesn't look bad. It of course needs improvement
> but I've also seen worse specimens from people being actually paid for
> writing the code.
>
> Remember that "how to make things better" is a function of few parameters:
> - what you want to achieve
> - what are you able to do
> - how much time do you have
>
> If your sole goal is to learn and improve skills, I would recommend
> polishing this in current procedural fashion to some extent, but not trying
> to make it perfect. Then I would start from scratch and experiment with
> different paradigms (OOP for instance). Then I would try to make a smaller
> project that has some actual utility.
>

Yes, I was pretty much interested in Python at the end 90s however life
made me putting this hobby away and now life changed again so I've more
free time and I'm happy be back with Python so after couple months
learning it again and writing few liners this is first thing that got me
to use what I've learnt so far and gave opportunity to solve moany
problems I had to deal with (had few nights without sleep ) :-)
Now I'll learn OOP as you said and then try to made this program again
with OOP from scratch.

--
Thanks


From Bischoop at vimart.net  Thu Dec 17 11:20:16 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 16:20:16 -0000 (UTC)
Subject: Messed up syntax in Vim when pasting python code to post to the
 groups.
Message-ID: <slrnrtn1a0.54o.Bischoop@vimart.net>


I've being asked not to use external links for code sharing to the
groups but when I paste the code in to my vim editor I do use with slrn
client the code is just messed up. 
How dear people people using vim solved this?

From 2QdxY4RzWzUUiLuE at potatochowder.com  Thu Dec 17 11:31:45 2020
From: 2QdxY4RzWzUUiLuE at potatochowder.com (2QdxY4RzWzUUiLuE at potatochowder.com)
Date: Thu, 17 Dec 2020 10:31:45 -0600
Subject: Messed up syntax in Vim when pasting python code to post to the
 groups.
In-Reply-To: <slrnrtn1a0.54o.Bischoop@vimart.net>
References: <slrnrtn1a0.54o.Bischoop@vimart.net>
Message-ID: <X9uH8XsC/yoFscQY@scrozzle>

On 2020-12-17 at 16:20:16 -0000,
Bischoop <Bischoop at vimart.net> wrote:

> I've being asked not to use external links for code sharing to the
> groups but when I paste the code in to my vim editor I do use with
> slrn client the code is just messed up.

> How dear people people using vim solved this?

I'm not a vim user, but it just came up to look into the paste and
nopaste commands.

From torriem at gmail.com  Thu Dec 17 11:37:56 2020
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 17 Dec 2020 09:37:56 -0700
Subject: Review, suggestion etc?
In-Reply-To: <slrnrtn0o4.54o.Bischoop@vimart.net>
References: <slrnrtlgsk.drf.Bischoop@vimart.net>
 <slrnrtlho7.drf.Bischoop@vimart.net>
 <CAMkRj3GqXyFxEeRZUACYgrJ56B2JvKGfV+dRGd8EhnmOzCZBpg@mail.gmail.com>
 <mailman.448.1608206143.7193.python-list@python.org>
 <slrnrtn0o4.54o.Bischoop@vimart.net>
Message-ID: <1aabf08d-63e6-9a36-8130-f1aa26cccdff@gmail.com>

On 12/17/20 9:10 AM, Bischoop wrote:
> Could you expand here, I rather don't know how I could do it different
> way apart from if maritals == 'Yes' or maritals == 'No' or is it what
> you meant?

I think he's hinting at using a loop instead.

while maritals != 'Yes' and maritals != 'No':
    maritals = input('Married: Yes/No ?: ').title()

I think I got the logical condition right. Sometimes those are tricky!

From Bischoop at vimart.net  Thu Dec 17 11:42:46 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 16:42:46 -0000 (UTC)
Subject: Messed up syntax in Vim when pasting python code to post to the
 groups.
References: <slrnrtn1a0.54o.Bischoop@vimart.net>
Message-ID: <slrnrtn2k6.6ki.Bischoop@vimart.net>

On 2020-12-17, Bischoop <Bischoop at vimart.net> wrote:
>
> I've being asked not to use external links for code sharing to the
> groups but when I paste the code in to my vim editor I do use with slrn
> client the code is just messed up. 
> How dear people people using vim solved this?

Solved, partialy. Paste mode F2, however after pasting clicking F2 again
supposed to go to paste option OFF but in my case it's still pasting
without messing syntax, but yes I can paste with correct syntax.

--
Thanks

From Bischoop at vimart.net  Thu Dec 17 11:52:14 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 16:52:14 -0000 (UTC)
Subject: Messed up syntax in Vim when pasting python code to post to the
 groups.
References: <slrnrtn1a0.54o.Bischoop@vimart.net> <X9uH8XsC/yoFscQY@scrozzle>
 <mailman.452.1608222710.7193.python-list@python.org>
Message-ID: <slrnrtn35u.6ki.Bischoop@vimart.net>

On 2020-12-17, 2QdxY4RzWzUUiLuE at potatochowder.com <2QdxY4RzWzUUiLuE at potatochowder.com> wrote:
>
> I'm not a vim user, but it just came up to look into the paste and
> nopaste commands.

I've googled the matter and found pressing F2 toogles 'paste' mode and
then after pasting F2 again to switch off paste mode or manually 
:set paste
:set nopaste

https://vim.fandom.com/wiki/Toggle_auto-indenting_for_code_paste

--
Thanks

From Bischoop at vimart.net  Thu Dec 17 12:00:45 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 17:00:45 -0000 (UTC)
Subject: Review, suggestion etc?
References: <slrnrtlgsk.drf.Bischoop@vimart.net>
 <slrnrtlho7.drf.Bischoop@vimart.net>
 <CAMkRj3GqXyFxEeRZUACYgrJ56B2JvKGfV+dRGd8EhnmOzCZBpg@mail.gmail.com>
 <mailman.448.1608206143.7193.python-list@python.org>
 <slrnrtn0o4.54o.Bischoop@vimart.net>
 <1aabf08d-63e6-9a36-8130-f1aa26cccdff@gmail.com>
 <mailman.453.1608223080.7193.python-list@python.org>
Message-ID: <slrnrtn3lt.6ki.Bischoop@vimart.net>

On 2020-12-17, Michael Torrie <torriem at gmail.com> wrote:
> On 12/17/20 9:10 AM, Bischoop wrote:
>> Could you expand here, I rather don't know how I could do it different
>> way apart from if maritals == 'Yes' or maritals == 'No' or is it what
>> you meant?
>
> I think he's hinting at using a loop instead.
>
> while maritals != 'Yes' and maritals != 'No':
>     maritals = input('Married: Yes/No ?: ').title()
>
> I think I got the logical condition right. Sometimes those are tricky!

I think you're right.
Yes those are tricky sometimes :-)

Look how I had it previously:

    def marriage():
        maritals = input('Married: Yes/No ?: ').title()
        while maritals != 'Yes' and maritals != 'No':
            return marriage()
        return maritals
    marital = marriage()


When looking at it now I couldn't find the dumbest way for it.



From swistakm at gmail.com  Thu Dec 17 12:16:05 2020
From: swistakm at gmail.com (=?UTF-8?Q?Micha=C5=82_Jaworski?=)
Date: Thu, 17 Dec 2020 18:16:05 +0100
Subject: Review, suggestion etc?
In-Reply-To: <1aabf08d-63e6-9a36-8130-f1aa26cccdff@gmail.com>
References: <slrnrtlgsk.drf.Bischoop@vimart.net>
 <slrnrtlho7.drf.Bischoop@vimart.net>
 <CAMkRj3GqXyFxEeRZUACYgrJ56B2JvKGfV+dRGd8EhnmOzCZBpg@mail.gmail.com>
 <mailman.448.1608206143.7193.python-list@python.org>
 <slrnrtn0o4.54o.Bischoop@vimart.net>
 <1aabf08d-63e6-9a36-8130-f1aa26cccdff@gmail.com>
Message-ID: <CAMkRj3H4hPOr1P-FpkgZJxvs++LvG0mrX-XrdbyMQOtwfsB4Cg@mail.gmail.com>

> I think he's hinting at using a loop instead.
>
> while maritals != 'Yes' and maritals != 'No':
>    maritals = input('Married: Yes/No ?: ').title()

Exactly. I would go even further and make it a reusable function. Eg.

def prompt_choices(prompt, choices):
    choices = set(c.lower() for c in choices)
    while value := input(f"{prompt} {choices}:").lower() not in choices:
        pass
    return value

Or without := operator:

def prompt_choices(prompt, choices):
    value = None
    choices = set(c.lower() for c in choices)
    while value not in choices:
        input(f"{prompt} {choices}:").lower()
    return value

That way you can use it as follows:

marital = prompt_choices("Married", ["yes", "no"])

> So in other words I shoudn't nest functions like in
> changes(), add_people() etc but keep
> everything in one functions.

Simply move those functions outside of their "hosting" functions and
call them as they are. Also, many of them won't be needed anymore as you
introduce some generic helper functions (e.g. prompt_choices).

> Now I'll learn OOP as you said and then try to made this program again
> with OOP from scratch.

Recommend polishing the procedural approach a bit more too, though. Like
reducing code repetition. Looking into how data is stored, eg. can fields
be stored in CSV columns instead of JSON? OOP can be overwhelming at the
very beginning. For instance it can take some time learning what should be
an object and what shouldn't. You definitely can start adding e.g.
dataclasses because they are more like structures (e.g. struct in C
mentioned earlier).

czw., 17 gru 2020 o 17:38 Michael Torrie <torriem at gmail.com> napisa?(a):

> On 12/17/20 9:10 AM, Bischoop wrote:
> > Could you expand here, I rather don't know how I could do it different
> > way apart from if maritals == 'Yes' or maritals == 'No' or is it what
> > you meant?
>
> I think he's hinting at using a loop instead.
>
> while maritals != 'Yes' and maritals != 'No':
>     maritals = input('Married: Yes/No ?: ').title()
>
> I think I got the logical condition right. Sometimes those are tricky!
> --
> https://mail.python.org/mailman/listinfo/python-list
>

From Bischoop at vimart.net  Thu Dec 17 12:47:54 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 17:47:54 -0000 (UTC)
Subject: Review, suggestion etc?
References: <slrnrtlgsk.drf.Bischoop@vimart.net>
 <slrnrtlho7.drf.Bischoop@vimart.net>
 <CAMkRj3GqXyFxEeRZUACYgrJ56B2JvKGfV+dRGd8EhnmOzCZBpg@mail.gmail.com>
 <mailman.448.1608206143.7193.python-list@python.org>
 <slrnrtn0o4.54o.Bischoop@vimart.net>
 <1aabf08d-63e6-9a36-8130-f1aa26cccdff@gmail.com>
 <CAMkRj3H4hPOr1P-FpkgZJxvs++LvG0mrX-XrdbyMQOtwfsB4Cg@mail.gmail.com>
 <mailman.454.1608225377.7193.python-list@python.org>
Message-ID: <slrnrtn6ea.7d0.Bischoop@vimart.net>

On 2020-12-17, Micha? Jaworski <swistakm at gmail.com> wrote:
>
> Exactly. I would go even further and make it a reusable function. Eg.
>
> def prompt_choices(prompt, choices):
>     choices = set(c.lower() for c in choices)
>     while value := input(f"{prompt} {choices}:").lower() not in choices:
>         pass
>     return value
>
> Or without := operator:
>
> def prompt_choices(prompt, choices):
>     value = None
>     choices = set(c.lower() for c in choices)
>     while value not in choices:
>         input(f"{prompt} {choices}:").lower()
>     return value
>
> That way you can use it as follows:
>
> marital = prompt_choices("Married", ["yes", "no"])
>

Oh man that really not like they teach in tutorials.
These are the examples at which you look and think: moment, I need a few sec
to follow :-)


>> So in other words I shoudn't nest functions like in
>> changes(), add_people() etc but keep
>> everything in one functions.
>
> Simply move those functions outside of their "hosting" functions and
> call them as they are. Also, many of them won't be needed anymore as you
> introduce some generic helper functions (e.g. prompt_choices).
>


Honestly I've done it like that because I thought that would be more elegant
way to have how_old(), marriage() etc hosted in add_people() but I'm glad I've 
done this time because learn a bit, I had quite a problem to keep people
argument storing and returning in every function, I see it was unecessary
as I know now but another experience.

>> Now I'll learn OOP as you said and then try to made this program again
>> with OOP from scratch.
>
> Recommend polishing the procedural approach a bit more too, though. Like
> reducing code repetition. Looking into how data is stored, eg. can fields
> be stored in CSV columns instead of JSON? OOP can be overwhelming at the
> very beginning. For instance it can take some time learning what should be
> an object and what shouldn't. You definitely can start adding e.g.
> dataclasses because they are more like structures (e.g. struct in C
> mentioned earlier).
>

Right I keep it in mind. Yes, the storing you mention I'll have to
improve, even the json I've done sucks because I've noticed it storing
everything in one column lol I thought that json library handles it
itself but apparently I have to tell him about it to insert key,values
into different columns.

--
Dzieki 

From Bischoop at vimart.net  Thu Dec 17 12:55:28 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 17:55:28 -0000 (UTC)
Subject: Function returns old value
References: <slrnrt86vo.517.Bischoop@vimart.net> <rr185b$136c$1@ciao.gmane.io>
 <mailman.369.1607744941.7193.python-list@python.org>
 <slrnrtlh9j.drf.Bischoop@vimart.net>
 <5b8a1f0b-07a1-6bc7-39d3-b441adbb2010@DancesWithMice.info>
 <mailman.442.1608173788.7193.python-list@python.org>
 <slrnrtlipo.fgd.Bischoop@vimart.net>
 <6c4028ef-0359-098e-6066-87765d51fb6a@DancesWithMice.info>
 <mailman.443.1608175386.7193.python-list@python.org>
Message-ID: <slrnrtn6sf.7d0.Bischoop@vimart.net>

On 2020-12-17, dn <PythonList at DancesWithMice.info> wrote:
>> After expiry, any posts 'here' with links to 'there', will be useless.
>> 
>> I do mind that however I thoght it better if paste a whole code to see
>> and pasting from my IDE to vim/slrn was messing syntax, I'll do better
>> next time.
>
>
> Yes, it can be difficult to know how much code to include and how much 
> can be left-out. Don't worry about that - replies can always trim any 
> excess.
>

I solved the pasting problem but about triming the excess, well
some people don't give a fuck and don't cut unecessary lines.
I'm pretty sure that if I post a 100 line code, some will reply without
cutting it just to point what's wrong in line 50 lol.




> Also, don't be concerned about such comments. Rather than complaints, 
> please regard them as advice from folk who have been 'here' and/or using 
> Python for some time.

I'm not concerned at all :-) 
I'm using newsgroups,irc for good over 20 years so I don't bother.

--
Thanks


From Bischoop at vimart.net  Thu Dec 17 13:05:09 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 18:05:09 -0000 (UTC)
Subject: Function returns old value
References: <slrnrt86vo.517.Bischoop@vimart.net> <rr185b$136c$1@ciao.gmane.io>
 <mailman.369.1607744941.7193.python-list@python.org>
 <slrnrtlh9j.drf.Bischoop@vimart.net>
 <5b8a1f0b-07a1-6bc7-39d3-b441adbb2010@DancesWithMice.info>
 <mailman.442.1608173788.7193.python-list@python.org>
 <slrnrtlipo.fgd.Bischoop@vimart.net> <20201217095751.GA8064@hjp.at>
 <mailman.444.1608199075.7193.python-list@python.org>
Message-ID: <slrnrtn7ek.7d0.Bischoop@vimart.net>

On 2020-12-17, Peter J. Holzer <hjp-python at hjp.at> wrote:
>
> --EVF5PPMfhYS0aIcm
> Content-Type: text/plain; charset=us-ascii
> Content-Disposition: inline
> Content-Transfer-Encoding: quoted-printable
>
> On 2020-12-17 03:06:32 -0000, Bischoop wrote:
>> pasting from my IDE to vim/slrn was messing syntax,
>
> You can=20
>
>:set paste

Indeed, thanks I just didn't come to conclusion that it has to be special
paste mode to paste without breaking the lines. 
Also  adding in * set pastetoggle=<F2> * in vimrc activates paste
mode when pressing F2, I find it more convenient.
>

From arj.python at gmail.com  Thu Dec 17 14:52:07 2020
From: arj.python at gmail.com (Abdur-Rahmaan Janhangeer)
Date: Thu, 17 Dec 2020 23:52:07 +0400
Subject: Lambda in parameters
Message-ID: <CADrxXX=yU2cyv_9JzKZ+F5StJJC0J-iwX+OM8CQrFgUwL41QFw@mail.gmail.com>

Greetings list,

Here is a famous question's solution

def cons(a, b):
    def pair(f):
        return f(a, b)
    return pair

def car(c):
    return c(lambda a, b: a)

print(cons(1, 2)(lambda a, b: a))
print(car(cons(1, 2)))

The aim of car is to return 1


but i don't understand how lambda achieves this

Kind Regards,


Abdur-Rahmaan Janhangeer

https://www.github.com/Abdur-RahmaanJ

Mauritius

sent from gmail client on Android, that's why the signature is so ugly.

From mstemper at gmail.com  Thu Dec 17 15:22:41 2020
From: mstemper at gmail.com (Michael F. Stemper)
Date: Thu, 17 Dec 2020 14:22:41 -0600
Subject: Function returns old value
In-Reply-To: <mailman.444.1608199075.7193.python-list@python.org>
References: <slrnrt86vo.517.Bischoop@vimart.net> <rr185b$136c$1@ciao.gmane.io>
 <mailman.369.1607744941.7193.python-list@python.org>
 <slrnrtlh9j.drf.Bischoop@vimart.net>
 <5b8a1f0b-07a1-6bc7-39d3-b441adbb2010@DancesWithMice.info>
 <mailman.442.1608173788.7193.python-list@python.org>
 <slrnrtlipo.fgd.Bischoop@vimart.net> <20201217095751.GA8064@hjp.at>
 <mailman.444.1608199075.7193.python-list@python.org>
Message-ID: <rrgemh$77h$1@dont-email.me>

On 17/12/2020 03.57, Peter J. Holzer wrote:
> On 2020-12-17 03:06:32 -0000, Bischoop wrote:
>> pasting from my IDE to vim/slrn was messing syntax,
> 
> You can
> 
> :set paste
> 
> in vim to prevent it from messing with pasted content (don't forget to
> set nopaste afterwards).

What's the difference between that and
:set ai
and
:set noai

> With newer vims that's rarely necessary though since they can distinguish
> between input that was pasted and input that was typed.

I thought that I was going nuts when I encountered that. Any idea how to
defeat such a so-called 'feature"?


-- 
Michael F. Stemper
The name of the story is "A Sound of Thunder".
It was written by Ray Bradbury. You're welcome.

From rshepard at appl-ecosys.com  Thu Dec 17 17:29:30 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Thu, 17 Dec 2020 14:29:30 -0800 (PST)
Subject: setuptools issue
Message-ID: <alpine.LNX.2.20.2012171423580.8182@salmo.appl-ecosys.com>

I want to use tkcalendar and dateentry in my application but have problems
with tkcalendar's dependency on babel and setuptools.

When I try to build babel it fails:
Traceback (most recent call last):
   File "/tmp/SBo/babel-2.8.1/setup.py", line 7, in <module>
     from setuptools import setup
ModuleNotFoundError: No module named 'setuptools'

Installed on this Slackware-14.2/x86_64 workstation with python-3.9.1 are:
python-setuptools-22.0.5-x86_64-1
setuptools-git-1.1-x86_64-1_SBo
setuptools-scm-3.3.3-x86_64-1_SBo

Please advise me how I diagnose the reason babel's setup.py cannot find a
suitable setuptools.

TIA,

Rich


From Bischoop at vimart.net  Thu Dec 17 18:04:26 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 23:04:26 -0000 (UTC)
Subject: Review, suggestion etc?
References: <slrnrtlgsk.drf.Bischoop@vimart.net>
 <slrnrtlho7.drf.Bischoop@vimart.net>
 <CAMkRj3GqXyFxEeRZUACYgrJ56B2JvKGfV+dRGd8EhnmOzCZBpg@mail.gmail.com>
 <mailman.448.1608206143.7193.python-list@python.org>
 <slrnrtn0o4.54o.Bischoop@vimart.net>
 <o5gntf9hji28id57kcmk15rrfpgaarsl4f@4ax.com>
 <mailman.456.1608238265.7193.python-list@python.org>
Message-ID: <slrnrtnovq.8du.Bischoop@vimart.net>

On 2020-12-17, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
>>
>
> 	The main concern is that you are using a RECURSIVE call. It is much
> better for such input checking to use an ITERATIVE (loop) scheme.
>
> 	def marriage():
> 		#loop forever
> 		while True:
> 			#get response from user
> 			maritals = input("Married: Yes/No ?").title()
> 			#if response is good, exit (break) the loop
> 			if maritals in ["Yes", "No"]: break
> 			#otherwise display error message and repeat loop
> 			print("Try again. Please respond with Yes or No")
> 		#return valid response
> 		return maritals
> 	
>
It makes sense for me now, better logic used here than mine. 
I've never met that way used in * if maritals in ['Yes', No']: * ,
it makes code elegant. 
So it's not good to use calling function itself (recursive call), I get it now.

From Bischoop at vimart.net  Thu Dec 17 18:05:46 2020
From: Bischoop at vimart.net (Bischoop)
Date: Thu, 17 Dec 2020 23:05:46 -0000 (UTC)
Subject: Review, suggestion etc?
References: <slrnrtlgsk.drf.Bischoop@vimart.net>
 <slrnrtlho7.drf.Bischoop@vimart.net>
 <CAMkRj3GqXyFxEeRZUACYgrJ56B2JvKGfV+dRGd8EhnmOzCZBpg@mail.gmail.com>
 <mailman.448.1608206143.7193.python-list@python.org>
 <slrnrtn0o4.54o.Bischoop@vimart.net>
 <o5gntf9hji28id57kcmk15rrfpgaarsl4f@4ax.com>
 <mailman.456.1608238265.7193.python-list@python.org>
 <slrnrtnovq.8du.Bischoop@vimart.net>
Message-ID: <slrnrtnp2a.8du.Bischoop@vimart.net>

On 2020-12-17, Bischoop <Bischoop at vimart.net> wrote:
> On 2020-12-17, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
>>>
>>
>> 	The main concern is that you are using a RECURSIVE call. It is much
>> better for such input checking to use an ITERATIVE (loop) scheme.
>>
>> 	def marriage():
>> 		#loop forever
>> 		while True:
>> 			#get response from user
>> 			maritals = input("Married: Yes/No ?").title()
>> 			#if response is good, exit (break) the loop
>> 			if maritals in ["Yes", "No"]: break
>> 			#otherwise display error message and repeat loop
>> 			print("Try again. Please respond with Yes or No")
>> 		#return valid response
>> 		return maritals
>> 	
>>
> It makes sense for me now, better logic used here than mine. 
> I've never met that way used in * if maritals in ['Yes', No']: * ,
> it makes code elegant. 
> So it's not good to use calling function itself (recursive call), I get it now.

--
Thanks

From jcasale at activenetwerx.com  Thu Dec 17 19:05:12 2020
From: jcasale at activenetwerx.com (Joseph L. Casale)
Date: Fri, 18 Dec 2020 00:05:12 +0000
Subject: setuptools issue
In-Reply-To: <alpine.LNX.2.20.2012171423580.8182@salmo.appl-ecosys.com>
References: <alpine.LNX.2.20.2012171423580.8182@salmo.appl-ecosys.com>
Message-ID: <118586e610d849dca2b10325dd0cd1bf@activenetwerx.com>

> Installed on this Slackware-14.2/x86_64 workstation with python-3.9.1 are:
> python-setuptools-22.0.5-x86_64-1

I just ran into this recently, I don't recall the actual source but it was the version
of setuptools having been so old. Your version is from Jun 3, 2016...

Update it, that was what worked for me.

jlc

From pfeiffer at cs.nmsu.edu  Thu Dec 17 20:17:32 2020
From: pfeiffer at cs.nmsu.edu (Joe Pfeiffer)
Date: Thu, 17 Dec 2020 18:17:32 -0700
Subject: Review, suggestion etc?
References: <slrnrtlgsk.drf.Bischoop@vimart.net>
 <slrnrtlho7.drf.Bischoop@vimart.net>
 <CAMkRj3GqXyFxEeRZUACYgrJ56B2JvKGfV+dRGd8EhnmOzCZBpg@mail.gmail.com>
 <mailman.448.1608206143.7193.python-list@python.org>
 <slrnrtn0o4.54o.Bischoop@vimart.net>
 <o5gntf9hji28id57kcmk15rrfpgaarsl4f@4ax.com>
 <mailman.456.1608238265.7193.python-list@python.org>
 <slrnrtnovq.8du.Bischoop@vimart.net>
Message-ID: <1btusjap5f.fsf@pfeifferfamily.net>

Bischoop <Bischoop at vimart.net> writes:

> On 2020-12-17, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
>>>
>>
>> 	The main concern is that you are using a RECURSIVE call. It is much
>> better for such input checking to use an ITERATIVE (loop) scheme.
>>
>> 	def marriage():
>> 		#loop forever
>> 		while True:
>> 			#get response from user
>> 			maritals = input("Married: Yes/No ?").title()
>> 			#if response is good, exit (break) the loop
>> 			if maritals in ["Yes", "No"]: break
>> 			#otherwise display error message and repeat loop
>> 			print("Try again. Please respond with Yes or No")
>> 		#return valid response
>> 		return maritals
>> 	
>>
> It makes sense for me now, better logic used here than mine. 
> I've never met that way used in * if maritals in ['Yes', No']: * ,
> it makes code elegant. 
> So it's not good to use calling function itself (recursive call), I get it now.

Recursion has very limited application, but where it's the right tool
it's invaluable (top-down parsers, some graph algorithms...).  We teach
it primarily because by the time a student has a good handle on how to
write a recursive function they understand functions in general really well.

From grant.b.edwards at gmail.com  Thu Dec 17 23:02:18 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Fri, 18 Dec 2020 04:02:18 -0000 (UTC)
Subject: Review, suggestion etc?
References: <slrnrtlgsk.drf.Bischoop@vimart.net>
 <slrnrtlho7.drf.Bischoop@vimart.net>
 <CAMkRj3GqXyFxEeRZUACYgrJ56B2JvKGfV+dRGd8EhnmOzCZBpg@mail.gmail.com>
 <mailman.448.1608206143.7193.python-list@python.org>
 <slrnrtn0o4.54o.Bischoop@vimart.net>
 <o5gntf9hji28id57kcmk15rrfpgaarsl4f@4ax.com>
 <mailman.456.1608238265.7193.python-list@python.org>
 <slrnrtnovq.8du.Bischoop@vimart.net> <1btusjap5f.fsf@pfeifferfamily.net>
Message-ID: <rrh9k9$s5r$2@ciao.gmane.io>

On 2020-12-18, Joe Pfeiffer <pfeiffer at cs.nmsu.edu> wrote:

> Recursion has very limited application, but where it's the right
> tool it's invaluable (top-down parsers, some graph algorithms...).
> We teach it primarily because by the time a student has a good
> handle on how to write a recursive function they understand
> functions in general really well.

Yep, there are definitly cases where it's pretty much the only right
answer. If you try to avoid it, you end up writing what turns into a
simulation of recursion -- and doing that correctly isn't easy.

--
Grant





From cs at cskk.id.au  Fri Dec 18 01:02:42 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Fri, 18 Dec 2020 17:02:42 +1100
Subject: Lambda in parameters
In-Reply-To: <CADrxXX=yU2cyv_9JzKZ+F5StJJC0J-iwX+OM8CQrFgUwL41QFw@mail.gmail.com>
References: <CADrxXX=yU2cyv_9JzKZ+F5StJJC0J-iwX+OM8CQrFgUwL41QFw@mail.gmail.com>
Message-ID: <20201218060242.GA45279@cskk.homeip.net>

On 17Dec2020 23:52, Abdur-Rahmaan Janhangeer <arj.python at gmail.com> wrote:
>Here is a famous question's solution

These look like implementations of Lisp operators, which I've never 
found easy to remember. So I'll do this from first principles, but 
looking at the (uncommented) code.

This is some gratuitiously tricky code. Maybe that's needed for these 
operators. But there's a lot here, so let's unpick it:

>def cons(a, b):
>    def pair(f):
>        return f(a, b)
>    return pair

Cons returns "pair", a function which itself accepts a function "f", 
calls it with 2 values "a, b" and returns the result. For ultra 
trickiness, those 2 values "a, b" are the ones you passed to the initial 
call to cons().

This last bit is a closure: when you define a function, any nonlocal 
variables (those you use but never assign to) have the defining scope 
available for finding them. So the "pair" function gets "a" and "b" from 
those you passed to "cons".

Anyway, cons() returns a "pair" function hooked to the "a" and "b" you 
called it with.

>def car(c):
>    return c(lambda a, b: a)

The function accepts a function, and calls that function with "lambda a, 
b: a", which is itself a function which returns its first argument. You 
could write car like this:

    def car(c):
        def first(a, b):
            return a
        return c(first)

The lambda is just a way to write a simple single expression function.

>print(cons(1, 2)(lambda a, b: a))

What is "cons(1,2)". That returns a "pair" function hooked up to the a=1 
and b=2 values you supplied. And the pair function accepts a function of 
2 variables.

What does this do?

    cons(1, 2)(lambda a, b: a)

This takes the function returns by cons(1,2) and _calls_ that with a 
simple function which accepts 2 values and returns the first of them.

So:

    cons(1,2) => "pair function hooked to a=1 and b=2"

Then call:

    pair(lambda a, b: a)

which sets "f" to the lambda function, can calls that with (a,b). So it 
calls the lambda function with (1,2). Which returns 1.

>print(car(cons(1, 2)))

The "car" function pretty much just embodies the call-with-the-lambda.

>but i don't understand how lambda achieves this

If you rewite the lambda like this:

    def a_from_ab(a,b):
        return a

and then rewrite the first call to cons() like this:

    cons(1,2)(a_from_ab)

does it make any more sense?

Frankly, I think this is a terrible way to solve this problem, whatever 
the problem was supposed to be - that is not clear.

On the other hand, I presume it does implement the Lisp cons and car 
functions. I truly have no idea, I just remember these names from my 
brief brush with Lisp in the past.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From cs at cskk.id.au  Fri Dec 18 01:09:43 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Fri, 18 Dec 2020 17:09:43 +1100
Subject: Function returns old value
In-Reply-To: <rrgemh$77h$1@dont-email.me>
References: <rrgemh$77h$1@dont-email.me>
Message-ID: <20201218060943.GA42805@cskk.homeip.net>

On 17Dec2020 14:22, Michael F. Stemper <mstemper at gmail.com> wrote:
>On 17/12/2020 03.57, Peter J. Holzer wrote:
>>On 2020-12-17 03:06:32 -0000, Bischoop wrote:
>>>pasting from my IDE to vim/slrn was messing syntax,
>>
>>You can
>>
>>:set paste
>>
>>in vim to prevent it from messing with pasted content (don't forget to
>>set nopaste afterwards).
>
>What's the difference between that and
>:set ai
>and
>:set noai

Well, based on my experience (since the above is what I always do) that 
leave my automatic line folding and related "line wrapping" stuff still 
in play. Which I routinely have to repair if the pasted code is at all 
wide.

[ Experiments with ":set paste". ]

Yeah, the paste mode turns all that wrapping stuff off, and ":set 
nopaste" restores it intact. Ok, I guess I'm going to have to retrain my 
fingers now.

>>With newer vims that's rarely necessary though since they can 
>>distinguish
>>between input that was pasted and input that was typed.

Mine doesn't seem to (vim inside a MacOS iTerm).

>I thought that I was going nuts when I encountered that. Any idea how to
>defeat such a so-called 'feature"?

You mean having vim figure that out? I dunno. I came here from vi and 
haven't fully embraced al the stuff vim has.

I _did_ discover recently that somehow iTerm and/or vim knows about my 
vim split buffers and doesn't cross the entirely in-vim-curses window 
boundary, very very handy. I guess iTerm may know about terminal 
scrolling regions, if that's how vim implements the windowing stuff.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From auriocus at gmx.de  Fri Dec 18 07:05:26 2020
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Fri, 18 Dec 2020 13:05:26 +0100
Subject: Function returns old value
In-Reply-To: <rrgemh$77h$1@dont-email.me>
References: <slrnrt86vo.517.Bischoop@vimart.net> <rr185b$136c$1@ciao.gmane.io>
 <mailman.369.1607744941.7193.python-list@python.org>
 <slrnrtlh9j.drf.Bischoop@vimart.net>
 <5b8a1f0b-07a1-6bc7-39d3-b441adbb2010@DancesWithMice.info>
 <mailman.442.1608173788.7193.python-list@python.org>
 <slrnrtlipo.fgd.Bischoop@vimart.net> <20201217095751.GA8064@hjp.at>
 <mailman.444.1608199075.7193.python-list@python.org>
 <rrgemh$77h$1@dont-email.me>
Message-ID: <rri5u6$9j7$1@dont-email.me>

Am 17.12.20 um 21:22 schrieb Michael F. Stemper:
> On 17/12/2020 03.57, Peter J. Holzer wrote:
>> On 2020-12-17 03:06:32 -0000, Bischoop wrote:
>>> pasting from my IDE to vim/slrn was messing syntax,
>>
>> You can
>>
>> :set paste
>>
>> in vim to prevent it from messing with pasted content (don't forget to
>> set nopaste afterwards).
> 
> What's the difference between that and
> :set ai
> and
> :set noai
> 
>> With newer vims that's rarely necessary though since they can distinguish
>> between input that was pasted and input that was typed.
> 
> I thought that I was going nuts when I encountered that. Any idea how to
> defeat such a so-called 'feature"?

Use "gvim" instead of "vim" in a Terminal. The problems arises because 
vim in the terminal simply gets the input and "thinks" that you typed 
that stuff in, for which it does auto-indenting. gvim, OTOH, doe sthe 
pasting by itself. It also has other useful features like menus and 
popup-dialogs for searching etc.

	Christian


From arj.python at gmail.com  Fri Dec 18 09:20:13 2020
From: arj.python at gmail.com (Abdur-Rahmaan Janhangeer)
Date: Fri, 18 Dec 2020 18:20:13 +0400
Subject: Lambda in parameters
In-Reply-To: <20201218060242.GA45279@cskk.homeip.net>
References: <CADrxXX=yU2cyv_9JzKZ+F5StJJC0J-iwX+OM8CQrFgUwL41QFw@mail.gmail.com>
 <20201218060242.GA45279@cskk.homeip.net>
Message-ID: <CADrxXXmuVem4Q030jPrDMFtq3udXYBEW1WAwSM2863gn-_WBgw@mail.gmail.com>

The Question:

# ---
This problem was asked by Jane Street.

cons(a, b) constructs a pair, and car(pair) and cdr(pair) returns the first
and last element of that pair. For example, car(cons(3, 4)) returns 3, and
cdr(cons(3, 4)) returns 4.

Given this implementation of cons:

def cons(a, b):
    def pair(f):
        return f(a, b)
    return pair

Implement car and cdr.
# ---

Kind Regards,


Abdur-Rahmaan Janhangeer

https://www.github.com/Abdur-RahmaanJ

Mauritius

sent from gmail client on Android, that's why the signature is so ugly.

On Fri, 18 Dec 2020, 10:02 Cameron Simpson, <cs at cskk.id.au> wrote:

> On 17Dec2020 23:52, Abdur-Rahmaan Janhangeer <arj.python at gmail.com> wrote:
> >Here is a famous question's solution
>
> These look like implementations of Lisp operators, which I've never
> found easy to remember. So I'll do this from first principles, but
> looking at the (uncommented) code.
>
> This is some gratuitiously tricky code. Maybe that's needed for these
> operators. But there's a lot here, so let's unpick it:
>
> >def cons(a, b):
> >    def pair(f):
> >        return f(a, b)
> >    return pair
>
> Cons returns "pair", a function which itself accepts a function "f",
> calls it with 2 values "a, b" and returns the result. For ultra
> trickiness, those 2 values "a, b" are the ones you passed to the initial
> call to cons().
>
> This last bit is a closure: when you define a function, any nonlocal
> variables (those you use but never assign to) have the defining scope
> available for finding them. So the "pair" function gets "a" and "b" from
> those you passed to "cons".
>
> Anyway, cons() returns a "pair" function hooked to the "a" and "b" you
> called it with.
>
> >def car(c):
> >    return c(lambda a, b: a)
>
> The function accepts a function, and calls that function with "lambda a,
> b: a", which is itself a function which returns its first argument. You
> could write car like this:
>
>     def car(c):
>         def first(a, b):
>             return a
>         return c(first)
>
> The lambda is just a way to write a simple single expression function.
>
> >print(cons(1, 2)(lambda a, b: a))
>
> What is "cons(1,2)". That returns a "pair" function hooked up to the a=1
> and b=2 values you supplied. And the pair function accepts a function of
> 2 variables.
>
> What does this do?
>
>     cons(1, 2)(lambda a, b: a)
>
> This takes the function returns by cons(1,2) and _calls_ that with a
> simple function which accepts 2 values and returns the first of them.
>
> So:
>
>     cons(1,2) => "pair function hooked to a=1 and b=2"
>
> Then call:
>
>     pair(lambda a, b: a)
>
> which sets "f" to the lambda function, can calls that with (a,b). So it
> calls the lambda function with (1,2). Which returns 1.
>
> >print(car(cons(1, 2)))
>
> The "car" function pretty much just embodies the call-with-the-lambda.
>
> >but i don't understand how lambda achieves this
>
> If you rewite the lambda like this:
>
>     def a_from_ab(a,b):
>         return a
>
> and then rewrite the first call to cons() like this:
>
>     cons(1,2)(a_from_ab)
>
> does it make any more sense?
>
> Frankly, I think this is a terrible way to solve this problem, whatever
> the problem was supposed to be - that is not clear.
>
> On the other hand, I presume it does implement the Lisp cons and car
> functions. I truly have no idea, I just remember these names from my
> brief brush with Lisp in the past.
>
> Cheers,
> Cameron Simpson <cs at cskk.id.au>
> --
> https://mail.python.org/mailman/listinfo/python-list
>

From pfeiffer at cs.nmsu.edu  Fri Dec 18 11:12:11 2020
From: pfeiffer at cs.nmsu.edu (Joe Pfeiffer)
Date: Fri, 18 Dec 2020 09:12:11 -0700
Subject: Review, suggestion etc?
References: <slrnrtlgsk.drf.Bischoop@vimart.net>
 <slrnrtlho7.drf.Bischoop@vimart.net>
 <CAMkRj3GqXyFxEeRZUACYgrJ56B2JvKGfV+dRGd8EhnmOzCZBpg@mail.gmail.com>
 <mailman.448.1608206143.7193.python-list@python.org>
 <slrnrtn0o4.54o.Bischoop@vimart.net>
 <o5gntf9hji28id57kcmk15rrfpgaarsl4f@4ax.com>
 <mailman.456.1608238265.7193.python-list@python.org>
 <slrnrtnovq.8du.Bischoop@vimart.net>
 <1btusjap5f.fsf@pfeifferfamily.net> <rrh9k9$s5r$2@ciao.gmane.io>
 <mailman.459.1608266027.7193.python-list@python.org>
Message-ID: <1bpn379jqc.fsf@pfeifferfamily.net>

Grant Edwards <grant.b.edwards at gmail.com> writes:


> On 2020-12-18, Joe Pfeiffer <pfeiffer at cs.nmsu.edu> wrote:
>
>> Recursion has very limited application, but where it's the right
>> tool it's invaluable (top-down parsers, some graph algorithms...).
>> We teach it primarily because by the time a student has a good
>> handle on how to write a recursive function they understand
>> functions in general really well.
>
> Yep, there are definitly cases where it's pretty much the only right
> answer. If you try to avoid it, you end up writing what turns into a
> simulation of recursion -- and doing that correctly isn't easy.

Decades ago I had to write a binary tree search in FORTRAN IV.  It
wasn't pretty.

From barry at barrys-emacs.org  Fri Dec 18 11:19:08 2020
From: barry at barrys-emacs.org (Barry)
Date: Fri, 18 Dec 2020 16:19:08 +0000
Subject: Lambda in parameters
In-Reply-To: <CADrxXXmuVem4Q030jPrDMFtq3udXYBEW1WAwSM2863gn-_WBgw@mail.gmail.com>
References: <CADrxXXmuVem4Q030jPrDMFtq3udXYBEW1WAwSM2863gn-_WBgw@mail.gmail.com>
Message-ID: <4801D5FB-BA12-494B-B971-508F99F6B0C6@barrys-emacs.org>



> On 18 Dec 2020, at 14:23, Abdur-Rahmaan Janhangeer <arj.python at gmail.com> wrote:
> 
> ?The Question:
> 
> # ---
> This problem was asked by Jane Street.
> 
> cons(a, b) constructs a pair, and car(pair) and cdr(pair) returns the first
> and last element of that pair. For example, car(cons(3, 4)) returns 3, and
> cdr(cons(3, 4)) returns 4.
> 
> Given this implementation of cons:
> 
> def cons(a, b):
>    def pair(f):
>        return f(a, b)
>    return pair
> 
> Implement car and cdr.
 Why car and cdr?

Well obviously car is content of the address register and cdr is content of data register.
Apparently an artefact of a early implementation of lisp.

Barry

> # ---
> 
> Kind Regards,
> 
> 
> Abdur-Rahmaan Janhangeer
> 
> https://www.github.com/Abdur-RahmaanJ
> 
> Mauritius
> 
> sent from gmail client on Android, that's why the signature is so ugly.
> 
>> On Fri, 18 Dec 2020, 10:02 Cameron Simpson, <cs at cskk.id.au> wrote:
>> 
>>> On 17Dec2020 23:52, Abdur-Rahmaan Janhangeer <arj.python at gmail.com> wrote:
>>> Here is a famous question's solution
>> 
>> These look like implementations of Lisp operators, which I've never
>> found easy to remember. So I'll do this from first principles, but
>> looking at the (uncommented) code.
>> 
>> This is some gratuitiously tricky code. Maybe that's needed for these
>> operators. But there's a lot here, so let's unpick it:
>> 
>>> def cons(a, b):
>>>   def pair(f):
>>>       return f(a, b)
>>>   return pair
>> 
>> Cons returns "pair", a function which itself accepts a function "f",
>> calls it with 2 values "a, b" and returns the result. For ultra
>> trickiness, those 2 values "a, b" are the ones you passed to the initial
>> call to cons().
>> 
>> This last bit is a closure: when you define a function, any nonlocal
>> variables (those you use but never assign to) have the defining scope
>> available for finding them. So the "pair" function gets "a" and "b" from
>> those you passed to "cons".
>> 
>> Anyway, cons() returns a "pair" function hooked to the "a" and "b" you
>> called it with.
>> 
>>> def car(c):
>>>   return c(lambda a, b: a)
>> 
>> The function accepts a function, and calls that function with "lambda a,
>> b: a", which is itself a function which returns its first argument. You
>> could write car like this:
>> 
>>    def car(c):
>>        def first(a, b):
>>            return a
>>        return c(first)
>> 
>> The lambda is just a way to write a simple single expression function.
>> 
>>> print(cons(1, 2)(lambda a, b: a))
>> 
>> What is "cons(1,2)". That returns a "pair" function hooked up to the a=1
>> and b=2 values you supplied. And the pair function accepts a function of
>> 2 variables.
>> 
>> What does this do?
>> 
>>    cons(1, 2)(lambda a, b: a)
>> 
>> This takes the function returns by cons(1,2) and _calls_ that with a
>> simple function which accepts 2 values and returns the first of them.
>> 
>> So:
>> 
>>    cons(1,2) => "pair function hooked to a=1 and b=2"
>> 
>> Then call:
>> 
>>    pair(lambda a, b: a)
>> 
>> which sets "f" to the lambda function, can calls that with (a,b). So it
>> calls the lambda function with (1,2). Which returns 1.
>> 
>>> print(car(cons(1, 2)))
>> 
>> The "car" function pretty much just embodies the call-with-the-lambda.
>> 
>>> but i don't understand how lambda achieves this
>> 
>> If you rewite the lambda like this:
>> 
>>    def a_from_ab(a,b):
>>        return a
>> 
>> and then rewrite the first call to cons() like this:
>> 
>>    cons(1,2)(a_from_ab)
>> 
>> does it make any more sense?
>> 
>> Frankly, I think this is a terrible way to solve this problem, whatever
>> the problem was supposed to be - that is not clear.
>> 
>> On the other hand, I presume it does implement the Lisp cons and car
>> functions. I truly have no idea, I just remember these names from my
>> brief brush with Lisp in the past.
>> 
>> Cheers,
>> Cameron Simpson <cs at cskk.id.au>
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>> 
> -- 
> https://mail.python.org/mailman/listinfo/python-list
> 


From rshepard at appl-ecosys.com  Fri Dec 18 11:25:05 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Fri, 18 Dec 2020 08:25:05 -0800 (PST)
Subject: setuptools issue
In-Reply-To: <118586e610d849dca2b10325dd0cd1bf@activenetwerx.com>
References: <alpine.LNX.2.20.2012171423580.8182@salmo.appl-ecosys.com>
 <118586e610d849dca2b10325dd0cd1bf@activenetwerx.com>
Message-ID: <alpine.LNX.2.20.2012180819110.24938@salmo.appl-ecosys.com>

On Fri, 18 Dec 2020, Joseph L. Casale wrote:

> I just ran into this recently, I don't recall the actual source but it was
> the version of setuptools having been so old. Your version is from Jun 3,
> 2016...
> Update it, that was what worked for me.

jlc,

Upgraded to python-setuptools-51.0.0-x86_64. Now when I try building
python3-babel it fails at this point:

running import_cldr
Extracting CLDR to '/tmp/SBo/babel-2.8.1/cldr/cldr-core-36'
Traceback (most recent call last):
   File "/tmp/SBo/babel-2.8.1/scripts/import_cldr.py", line 34, in <module>
     from babel import dates, numbers
   File "/tmp/SBo/babel-2.8.1/babel/dates.py", line 23, in <module>
     import pytz as _pytz
ModuleNotFoundError: No module named 'pytz'
## N.B.: pytz is installed here: pytz-2018.3-x86_64-1_SBo
## Could this also be too old? There's a pytz-2020.4 on PyPI

Traceback (most recent call last):
   File "/tmp/SBo/babel-2.8.1/scripts/download_import_cldr.py", line 104, in <module>
     main()
   File "/tmp/SBo/babel-2.8.1/scripts/download_import_cldr.py", line 97, in main
     subprocess.check_call([
   File "/usr/lib64/python3.9/subprocess.py", line 373, in check_call
     raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['/usr/bin/python3', '/tmp/SBo/babel-2.8.1/scripts/import_cldr.py', '/tmp/SBo/babel-2.8.1/cldr/cldr-core-36/common']' returned non-zero exit status 1.
Traceback (most recent call last):
   File "/tmp/SBo/babel-2.8.1/setup.py", line 30, in <module>
     setup(
   File "/usr/lib/python3.9/site-packages/setuptools/__init__.py", line 153, in setup
     return distutils.core.setup(**attrs)
   File "/usr/lib64/python3.9/distutils/core.py", line 148, in setup
     dist.run_commands()
   File "/usr/lib64/python3.9/distutils/dist.py", line 966, in run_commands
     self.run_command(cmd)
   File "/usr/lib64/python3.9/distutils/dist.py", line 985, in run_command
     cmd_obj.run()
   File "/tmp/SBo/babel-2.8.1/setup.py", line 27, in run
     subprocess.check_call([sys.executable, 'scripts/download_import_cldr.py'])
   File "/usr/lib64/python3.9/subprocess.py", line 373, in check_call
     raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['/usr/bin/python3', 'scripts/download_import_cldr.py']' returned non-zero exit status 1.

Regards,

Rich

From julio at diegidio.name  Fri Dec 18 11:26:42 2020
From: julio at diegidio.name (Julio Di Egidio)
Date: Fri, 18 Dec 2020 08:26:42 -0800 (PST)
Subject: Lambda in parameters
In-Reply-To: <mailman.462.1608301228.7193.python-list@python.org>
References: <CADrxXX=yU2cyv_9JzKZ+F5StJJC0J-iwX+OM8CQrFgUwL41QFw@mail.gmail.com>
 <CADrxXXmuVem4Q030jPrDMFtq3udXYBEW1WAwSM2863gn-_WBgw@mail.gmail.com>
 <20201218060242.GA45279@cskk.homeip.net>
 <mailman.462.1608301228.7193.python-list@python.org>
Message-ID: <f294a95a-4264-43d5-aeb2-7549a9aecaadn@googlegroups.com>

On Friday, 18 December 2020 at 15:20:59 UTC+1, Abdur-Rahmaan Janhangeer wrote:
> The Question: 
> 
> # --- 
> This problem was asked by Jane Street. 
> 
> cons(a, b) constructs a pair, and car(pair) and cdr(pair) returns the first 
> and last element of that pair. For example, car(cons(3, 4)) returns 3, and 
> cdr(cons(3, 4)) returns 4. 
> 
> Given this implementation of cons:
> def cons(a, b): 
> def pair(f): 
> return f(a, b) 
> return pair
> Implement car and cdr. 
> # --- 

Notice that you don't need (Python) lambdas to code it, plain function definitions are fine:

# ---
def cons(a, b):
    def pair(f):
        return f(a, b)
    return pair

def car(pair):
    def left(a, b):
        return a
    return pair(left)

pair = cons(1, 2)
assert car(pair) == 1
# ---

That said, few basic comments:  In Python, that 'cons' does not construct a pair, it rather returns a function with values a and b in its closure that, given some function, applies it to those values.  In fact, Python has tuples built-in, how to build them as well as how to access their members.  I take it the point of the exercise is how to use a purely functional language, such as here a fragment of Python, to encode (i.e. formalize) pairs and their operations.

Julio

From grant.b.edwards at gmail.com  Fri Dec 18 11:31:24 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Fri, 18 Dec 2020 16:31:24 -0000 (UTC)
Subject: Review, suggestion etc?
References: <slrnrtlgsk.drf.Bischoop@vimart.net>
 <slrnrtlho7.drf.Bischoop@vimart.net>
 <CAMkRj3GqXyFxEeRZUACYgrJ56B2JvKGfV+dRGd8EhnmOzCZBpg@mail.gmail.com>
 <mailman.448.1608206143.7193.python-list@python.org>
 <slrnrtn0o4.54o.Bischoop@vimart.net>
 <o5gntf9hji28id57kcmk15rrfpgaarsl4f@4ax.com>
 <mailman.456.1608238265.7193.python-list@python.org>
 <slrnrtnovq.8du.Bischoop@vimart.net> <1btusjap5f.fsf@pfeifferfamily.net>
 <rrh9k9$s5r$2@ciao.gmane.io>
 <mailman.459.1608266027.7193.python-list@python.org>
 <1bpn379jqc.fsf@pfeifferfamily.net>
Message-ID: <rrilgr$eae$1@ciao.gmane.io>

On 2020-12-18, Joe Pfeiffer <pfeiffer at cs.nmsu.edu> wrote:
> Grant Edwards <grant.b.edwards at gmail.com> writes:
>
>> Yep, there are definitly cases where it's pretty much the only right
>> answer. If you try to avoid it, you end up writing what turns into a
>> simulation of recursion -- and doing that correctly isn't easy.
>
> Decades ago I had to write a binary tree search in FORTRAN IV.  It
> wasn't pretty.

I saw somebody try to write a graph search in GW-BASIC once. It was a
huge mess, and wasn't anywhere close to working. Doing the same thing
recursively was trivial -- even in C. In Python it wuld have been
even trivialler.

--
Grant




From grant.b.edwards at gmail.com  Fri Dec 18 11:35:31 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Fri, 18 Dec 2020 16:35:31 -0000 (UTC)
Subject: Lambda in parameters
References: <CADrxXXmuVem4Q030jPrDMFtq3udXYBEW1WAwSM2863gn-_WBgw@mail.gmail.com>
 <4801D5FB-BA12-494B-B971-508F99F6B0C6@barrys-emacs.org>
Message-ID: <rriloj$eae$2@ciao.gmane.io>

On 2020-12-18, Barry <barry at barrys-emacs.org> wrote:
>> Implement car and cdr.
>  Why car and cdr?
>
> Well obviously car is content of the address register and cdr is content of data register.
> Apparently an artefact of a early implementation of lisp.

While car and cdr are lisp operators, the "content of address
register" and "content of data register" etymology is apparently
apocryphal:

  https://en.wikipedia.org/wiki/CAR_and_CDR#Etymology

--
Grant


From PythonList at DancesWithMice.info  Fri Dec 18 16:35:23 2020
From: PythonList at DancesWithMice.info (dn)
Date: Sat, 19 Dec 2020 10:35:23 +1300
Subject: "Worst bugs" and Python?
Message-ID: <fbccaa2d-a825-0324-c716-8eb866374e4c@etelligence.info>

TechRepublic have published a lovely piece of 'click-bait' featuring 
alarmist claims such as "open-source libraries are increasingly 
untrustworthy" whilst trotting-out tired, old, memes and bias.

Don't panic - hold-on to your PyPi!


<<<
The worst bugs in the top programming languages
by Brandon Vigliarolo in Security  on December 17, 2020, 9:32 AM PST
A heatmap shows PHP has the most flaws followed by C++, then Java, .Net, 
JavaScript, and Python in Veracode's annual security report.
 >>>
https://www.techrepublic.com/article/the-worst-bugs-in-the-top-programming-languages/

Does anyone think that code is 'bug free'? That's a 'filler topic' for 
any columnist lacking fresh ideas and desperate to fill a publishing 
deadline.

The basis is "State of Software Security v11" 'report' produced by 
Veracode (https://www.veracode.com/state-of-software-security-report). 
You will not be surprised to note that Veracode is in the business of 
marketing test and analysis software.

Any such report is inherently useful. They serve to ensure that we do 
not become complacent in our attitude to security. However, there are 
more "bugs" in software than fit under the heading of 'security'.

Similarly, at times the report appears to lump-together C, C++, and C#; 
whereas at others they may not; which makes it difficult to generalise 
or analyse. In the same vein, infographics look nice, but what does 
"Code Quality" really mean?

Another observation is that many of their 'categories' apply mainly to 
the on-line world. Corporation-only applications are protected by 
network defences rather than by their own devices.

A more interesting figure, which is under-reported both in the article 
and within Veracode's summaries, is the period of vulnerability - how 
long it takes to fix a bug after it has been reported - and preferably 
with the 'danger' of the bug factored-in. Thus a bug which doesn't allow 
the addition of new user-credentials is quite a different matter from 
one which allows existing users to upgrade themselves to 'super-user'. 
Such analysis is possibly available, but not in the summaries (above).

A quick dip into Veracode's 'vulnerability database' yielded the 
following intelligence:

Top three "library artefacts" with Python as [the only] keyword:
- firefox
- thunderbird
- linux-rt

Is Python 'counted' in these cases because it is involved somewhere 
within the package, because it is the majority-language used, because it 
is the only language employed, or because its use contributes to most of 
the faults-found?

Finally, such reports are primarily marketing tools, and thus notorious 
for bias or superficial content. Veracode do not declare the range, or 
limits on the range, of software they've analysed. Companies such as 
Microsoft and Oracle (plus, plus, ...) do not allow just-anyone to 
analyse their source-code - whereas 'open source' is available for 
analysis, by definition! An easy 'target' for shallow analysis?


At this point I gave up, lacking the interest to fill-out the 
contact-form, or to read the entire report.


The good news is, that of the six languages headlined in the summaries, 
Python comes-off 'best' (cf .Net, C++, Java, JavaScript, and PHP).
-- 
Regards,
=dn

From Joseph.Schachner at Teledyne.com  Fri Dec 18 17:41:42 2020
From: Joseph.Schachner at Teledyne.com (Schachner, Joseph)
Date: Fri, 18 Dec 2020 22:41:42 +0000
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <263519400.745131.1608052036522@mail.yahoo.com>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com>
Message-ID: <BN8PR14MB2851111169ABD05C57C4B62AF5C30@BN8PR14MB2851.namprd14.prod.outlook.com>

Yes.  In order to call D.get( ) it needs to pass two arguments.  The first is 'a', simple.  The second is the result of a call to get_default().   So, that is called.  From INSIDE get_default() it prints 'Nobody expects this' but you should expect it,  get_default() gets executed.   Following that it prints '1', because the default value was NOT USED.   If it was used, you would see 'Nobody expects this' followed by 0.

--- Joseph S.

-----Original Message-----
From: Mark Polesky <markpolesky at yahoo.com> 
Sent: Tuesday, December 15, 2020 12:07 PM
To: python-list at python.org
Subject: dict.get(key, default) evaluates default even if key exists

Hi.

# Running this script....

D = {'a':1}
def get_default():
??? print('Nobody expects this')
??? return 0
print(D.get('a', get_default()))

# ...generates this output:

Nobody expects this
1

###

Since I'm brand new to this community, I thought I'd ask here first... Is this worthy of a bug report?? This behavior is definitely unexpected to me, and I accidentally coded an endless loop in a mutual recursion situation because of it.? Calling dict.get.__doc__ only gives this short sentence: Return the value for key if key is in the dictionary, else default.? Nothing in that docstring suggests that the default value is evaluated even if the key exists, and I can't think of any good reason to do so.

Am I missing something?

Thanks,
Mark


From rshepard at appl-ecosys.com  Fri Dec 18 17:30:57 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Fri, 18 Dec 2020 14:30:57 -0800 (PST)
Subject: "Worst bugs" and Python?
In-Reply-To: <fbccaa2d-a825-0324-c716-8eb866374e4c@etelligence.info>
References: <fbccaa2d-a825-0324-c716-8eb866374e4c@etelligence.info>
Message-ID: <alpine.LNX.2.20.2012181426280.29974@salmo.appl-ecosys.com>

On Sat, 19 Dec 2020, dn via Python-list wrote:

> Companies such as Microsoft and Oracle (plus, plus, ...) do not allow
> just-anyone to analyse their source-code - whereas 'open source' is
> available for analysis, by definition! An easy 'target' for shallow
> analysis?

Looks bass-ackwards to me. That's the same argument made by proprietary
companies (especially Micro$oft) in the early 1990s. What falsifies the
writer's argument is all the malware that's affected Windoze over the past
couple of decades compared to F/OSS OSes and applications.

Sigh. Fake news hits the software industry.

Carpe weekend,

Rich

From mstemper at gmail.com  Sat Dec 19 09:46:05 2020
From: mstemper at gmail.com (Michael F. Stemper)
Date: Sat, 19 Dec 2020 08:46:05 -0600
Subject: Function returns old value
In-Reply-To: <mailman.461.1608271788.7193.python-list@python.org>
References: <rrgemh$77h$1@dont-email.me>
 <20201218060943.GA42805@cskk.homeip.net>
 <mailman.461.1608271788.7193.python-list@python.org>
Message-ID: <rrl3nn$vv0$1@dont-email.me>

On 18/12/2020 00.09, Cameron Simpson wrote:
> On 17Dec2020 14:22, Michael F. Stemper <mstemper at gmail.com> wrote:
>> On 17/12/2020 03.57, Peter J. Holzer wrote:
>>> On 2020-12-17 03:06:32 -0000, Bischoop wrote:

>>> With newer vims that's rarely necessary though since they can
>>> distinguish
>>> between input that was pasted and input that was typed.
> 
> Mine doesn't seem to (vim inside a MacOS iTerm).
> 
>> I thought that I was going nuts when I encountered that. Any idea how to
>> defeat such a so-called 'feature"?
> 
> You mean having vim figure that out? I dunno. I came here from vi and
> haven't fully embraced al the stuff vim has.

What I want is for vi to treat all input the same, whether it comes
directly from the keyboard, or from a copy/paste buffer.

It did everything fine from '92 when I started using it on AIX until a
year or two back when I briefly went to Ubuntu 18.04 LTS. Then, I could
paste a command into it, and it would insert it into the text, rather
than executing it. Or, I'd paste (in input mode; repeatedly verified)
some TeX and it would decide that it was really a command and execute
it.

And I've just realized which group this is, so my complaint is
completely off-topic. Sorry.

-- 
Michael F. Stemper
Deuteronomy 24:17

From meunier at ccs.neu.edu  Sat Dec 19 07:39:13 2020
From: meunier at ccs.neu.edu (Philippe Meunier)
Date: Sat, 19 Dec 2020 07:39:13 -0500
Subject: Lambda in parameters
In-Reply-To: <CADrxXXmuVem4Q030jPrDMFtq3udXYBEW1WAwSM2863gn-_WBgw@mail.gmail.com>
 <CADrxXX=yU2cyv_9JzKZ+F5StJJC0J-iwX+OM8CQrFgUwL41QFw@mail.gmail.com>
Message-ID: <X930cViyZCNf4MDh@login-students.ccs.neu.edu>

Abdur-Rahmaan Janhangeer wrote:
>The aim of car is to return 1
>but i don't understand how lambda achieves this

Cameron Simpson's explanation is very good.  See also the example reduction
here: https://en.wikipedia.org/wiki/Church_encoding#Church_pairs

>This problem was asked by Jane Street.

Jane Street is well known for its love of functional programming in general
and of OCaml in particular.  If you don't know OCaml yet, I highly
recommend it.  You can think of it as Python with (static) types.

Best,

Philippe



From lammenspaolo at gmail.com  Sat Dec 19 09:38:21 2020
From: lammenspaolo at gmail.com (Paolo Lammens)
Date: Sat, 19 Dec 2020 15:38:21 +0100
Subject: Delegating to part of a subgenerator
Message-ID: <CAK6OdHDO1B9LTM-+p4w+UB+GaQzFdj0V-NQ0h+Jwf9=8UrC5Ew@mail.gmail.com>

Dear all,

I've been struggling with the following problem, and I thought maybe there
is someone here in python-list who could shine some light on this.

Suppose we have a generator function `subgen`, and we want to wrap this in
another generator function, `gen`. For clarity, these are "full"
generators, i.e. they make use of .send, .throw, .close, etc. The purpose
of `gen` is to intercept the first value yielded by `subgen`, transforming
it in some form, and forwarding it on to the caller; after that, it should
just delegate to the rest of the generator iterator with `yield from`.

The problem is, the semantics of `yield from` expect a "fresh" generator
iterator, not a partially consumed generator. Indeed, the first value that
`yield from` will send to the iterator will be `None`, to start the
execution of the generator. But in this case we have already started the
generator, and to continue its execution we should really send whatever we
received after yielding the first value. However there's no way to specify
this with the `yield from` syntax.

A solution would be to re-implement the semantics of `yield from`, but with
an optional starting value (other than None) that will be sent to the
iterator as the initial value. However this means, as I said,
re-implementing the whole of `yield from`, i.e. handling .send(), .throw(),
.close(), etc., which is not ideal. So that would not be a good solution.
Am I asking for the impossible?

More details and an example in my original stackoverflow question:
https://stackoverflow.com/q/65369447/6117426

Best,

From cs at cskk.id.au  Sat Dec 19 16:24:59 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Sun, 20 Dec 2020 08:24:59 +1100
Subject: Lambda in parameters
In-Reply-To: <X930cViyZCNf4MDh@login-students.ccs.neu.edu>
References: <X930cViyZCNf4MDh@login-students.ccs.neu.edu>
Message-ID: <20201219212459.GA28218@cskk.homeip.net>

On 19Dec2020 07:39, Philippe Meunier <meunier at ccs.neu.edu> wrote:
>See also the example reduction
>here: https://en.wikipedia.org/wiki/Church_encoding#Church_pairs

Thank you for this reference. I've stuck it on my reading list.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From greg.ewing at canterbury.ac.nz  Sat Dec 19 17:52:59 2020
From: greg.ewing at canterbury.ac.nz (Greg Ewing)
Date: Sun, 20 Dec 2020 11:52:59 +1300
Subject: Lambda in parameters
In-Reply-To: <mailman.460.1608271375.7193.python-list@python.org>
References: <CADrxXX=yU2cyv_9JzKZ+F5StJJC0J-iwX+OM8CQrFgUwL41QFw@mail.gmail.com>
 <20201218060242.GA45279@cskk.homeip.net>
 <mailman.460.1608271375.7193.python-list@python.org>
Message-ID: <i47eibFgk4rU1@mid.individual.net>

On 18/12/20 7:02 pm, Cameron Simpson wrote:
> Frankly, I think this is a terrible way to solve this problem, whatever
> the problem was supposed to be - that is not clear.

It demonstrates that a programming language doesn't strictly
need data structes -- you can do everything with nothing
but functions.

This is mainly of theoretical interest; it's not usually a
practical way to go about things. But it's a good exercise
in thinking about functions as objects to be manipulated.

-- 
Greg

From arj.python at gmail.com  Sat Dec 19 22:47:36 2020
From: arj.python at gmail.com (Abdur-Rahmaan Janhangeer)
Date: Sun, 20 Dec 2020 07:47:36 +0400
Subject: Lambda in parameters
In-Reply-To: <20201218060242.GA45279@cskk.homeip.net>
References: <CADrxXX=yU2cyv_9JzKZ+F5StJJC0J-iwX+OM8CQrFgUwL41QFw@mail.gmail.com>
 <20201218060242.GA45279@cskk.homeip.net>
Message-ID: <CADrxXXmxH0fX_ae704DpvP7D53Ui2gHdDebixUW37M-cR-YGSg@mail.gmail.com>

Greetings,

Very clear explanations, rewriting lambdas as a function
was the key to understand it. Did not know was a lisp inspiration.

My mind still spiralling XD

Kind Regards,

Abdur-Rahmaan Janhangeer
about <https://compileralchemy.github.io/> | blog
<https://www.pythonkitchen.com>
github <https://github.com/Abdur-RahmaanJ>
Mauritius

From arj.python at gmail.com  Sat Dec 19 22:49:07 2020
From: arj.python at gmail.com (Abdur-Rahmaan Janhangeer)
Date: Sun, 20 Dec 2020 07:49:07 +0400
Subject: Lambda in parameters
In-Reply-To: <4801D5FB-BA12-494B-B971-508F99F6B0C6@barrys-emacs.org>
References: <CADrxXXmuVem4Q030jPrDMFtq3udXYBEW1WAwSM2863gn-_WBgw@mail.gmail.com>
 <4801D5FB-BA12-494B-B971-508F99F6B0C6@barrys-emacs.org>
Message-ID: <CADrxXXmbE=_gzPFW_xWJqESrNaRc6CrSM2KkVe_U+xk0Pt_w1A@mail.gmail.com>

Greetings list,


 Why car and cdr?

Well obviously car is content of the address register and cdr is content of
data register.
Apparently an artefact of a early implementation of lisp.

Oh did not know that detail. More twists for sure. Thought lisp did not go
lowlevel.

Kind Regards,

Abdur-Rahmaan Janhangeer
about <https://compileralchemy.github.io/> | blog
<https://www.pythonkitchen.com>
github <https://github.com/Abdur-RahmaanJ>
Mauritius

From arj.python at gmail.com  Sat Dec 19 22:52:32 2020
From: arj.python at gmail.com (Abdur-Rahmaan Janhangeer)
Date: Sun, 20 Dec 2020 07:52:32 +0400
Subject: Lambda in parameters
In-Reply-To: <X930cViyZCNf4MDh@login-students.ccs.neu.edu>
References: <CADrxXXmuVem4Q030jPrDMFtq3udXYBEW1WAwSM2863gn-_WBgw@mail.gmail.com>
 <CADrxXX=yU2cyv_9JzKZ+F5StJJC0J-iwX+OM8CQrFgUwL41QFw@mail.gmail.com>
 <X930cViyZCNf4MDh@login-students.ccs.neu.edu>
Message-ID: <CADrxXX=f+L6Q-n=ao643LXXoz2JT84kq01GpYSTFfFjpwLygFQ@mail.gmail.com>

Greetings list,


Jane Street is well known for its love of functional programming in general
and of OCaml in particular.  If you don't know OCaml yet, I highly
recommend it.  You can think of it as Python with (static) types.

Yes i know OCaml when i was exploring haskell and the like.
At that time i was looking for companies who use OCaml etc
Did not come across Jane Street (If you know someone from there
tell them the question writer has a really twisted mind ^^)/.
I don't understand why though you would prefer OCaml over Python, Go, Java
etc for a company ^^

Kind Regards,

Abdur-Rahmaan Janhangeer
about <https://compileralchemy.github.io/> | blog
<https://www.pythonkitchen.com>
github <https://github.com/Abdur-RahmaanJ>
Mauritius

From cl at isbd.net  Sun Dec 20 04:39:17 2020
From: cl at isbd.net (Chris Green)
Date: Sun, 20 Dec 2020 09:39:17 +0000
Subject: How do you find what exceptions a class can throw?
Message-ID: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>

I am using poplib.POP3_SSL() and I want to know what exceptions can be
thrown when I instantiate it.  Presumably it inherits them because
there's nothing much in the documentation page for poplib.POP3_SSL().

I specifically want to trap timeout exceptions.

(... and, yes, I know I should maybe move to IMAP but that's too much
work at the moment!)

-- 
Chris Green
?

From PythonList at DancesWithMice.info  Sun Dec 20 05:39:28 2020
From: PythonList at DancesWithMice.info (dn)
Date: Sun, 20 Dec 2020 23:39:28 +1300
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
References: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
Message-ID: <aa08a81b-f14d-9807-5af5-d95288e983e8@DancesWithMice.info>

On 20/12/2020 22:39, Chris Green wrote:
> I am using poplib.POP3_SSL() and I want to know what exceptions can be
> thrown when I instantiate it.  Presumably it inherits them because
> there's nothing much in the documentation page for poplib.POP3_SSL().
> 
> I specifically want to trap timeout exceptions.
> 
> (... and, yes, I know I should maybe move to IMAP but that's too much
> work at the moment!)


This morning, reading the results of the Virtual Python Core Developer 
Sprint 2020 
(https://pyfound.blogspot.com/2020/12/virtual-python-core-developer-sprint.html) 
and from there, PEP 594 -- Removing dead batteries from the standard 
library (https://www.python.org/dev/peps/pep-0594/), the impression 
gained is that the old/existing PSL offerings, eg poplib, are soon to be 
deprecated, in favor of asyncio and presumably something like aioimap 
(https://pypi.org/project/aioimaplib/).

Async handles with timeouts implicitly.

Apologies for the lack of direct-answer. That's as far as my reading has 
taken me. Hopefully someone, more in-the-know, will be able to advise...
-- 
Regards =dn

From roel at roelschroeven.net  Sat Dec 19 16:29:34 2020
From: roel at roelschroeven.net (Roel Schroeven)
Date: Sat, 19 Dec 2020 22:29:34 +0100
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <09aee7aa-146c-1c7f-1d0e-b800d7f4eac5@stoneleaf.us>
References: <263519400.745131.1608052036522.ref@mail.yahoo.com>
 <263519400.745131.1608052036522@mail.yahoo.com> <rrb0ug$88n$1@ciao.gmane.io>
 <mailman.404.1608059083.7193.python-list@python.org>
 <87bleu18s9.fsf@hornfels.zedat.fu-berlin.de>
 <92ed36a3e1fe6a3d3aaf5c935da1dc75402b172b.camel@anode.ca>
 <mailman.419.1608108124.7193.python-list@python.org>
 <87pn3ayvj2.fsf@hornfels.zedat.fu-berlin.de>
 <05df3a5f53b4d92a34f8399265a84b27f630da96.camel@anode.ca>
 <mailman.420.1608109951.7193.python-list@python.org>
 <87lfdyytwd.fsf@hornfels.zedat.fu-berlin.de>
 <CAPTjJmqZry5=wD-3GhQ87kHz-EKDJt5V9MiC=8R5pdDEqHidxw@mail.gmail.com>
 <09aee7aa-146c-1c7f-1d0e-b800d7f4eac5@stoneleaf.us>
Message-ID: <rrlrc1$1mi$1@ciao.gmane.io>

Ethan Furman schreef op 16/12/2020 om 17:59:
> Or, if the computationally massively expensive call uses potentially
> different arguments for each invocation:
> 
>       some_var = d.get('a') or cme(arg1, arg2, ...)

I don't like that because it is very fragile: the expression will 
evaluate to the second part not only when 'a' is not in the dictionary 
but also whenever the value corresponding to key 'a' is false-y.

Example:

     def slow_function(a, b):
         # Pretend this is slow, or there is any other reason for this
         # function to be called only when strictly necessary.
         print('slow_function called')
         return a + b

     d = {
         'spam': 0,
         'ham': 1,
         'parrot': 2,
     }

     some_var = d.get('spam') or slow_function(31, 11)
     print(some_var)

Result: slow_function is called, and some_var equals 42 instead of 0.

You could make it work reliable by using a unique sentinel value and the 
walrus operator:

     SENTINEL = object()
     some_var = (
         r
         if (r := d.get('spam', SENTINEL)) is not SENTINEL
         else slow_function(31, 11)
         )

But I don't like that either because it's way too complicated.

What could be useful in some use cases, I think, is a wrapper function 
that evaluates the function lazily:

     def dict_get_lazily(d, key, fnc, *args, **kwargs):
         try:
             return d[key]
         except KeyError:
             return fnc(*args, **kwargs)

     some_var = dict_get_lazily(d, 'spam', some_function, 31, 11)



-- 
"Honest criticism is hard to take, particularly from a relative, a
friend, an acquaintance, or a stranger."
         -- Franklin P. Jones

Roel Schroeven


From 2QdxY4RzWzUUiLuE at potatochowder.com  Sun Dec 20 08:45:50 2020
From: 2QdxY4RzWzUUiLuE at potatochowder.com (2QdxY4RzWzUUiLuE at potatochowder.com)
Date: Sun, 20 Dec 2020 07:45:50 -0600
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <rrlrc1$1mi$1@ciao.gmane.io>
References: <87bleu18s9.fsf@hornfels.zedat.fu-berlin.de>
 <92ed36a3e1fe6a3d3aaf5c935da1dc75402b172b.camel@anode.ca>
 <mailman.419.1608108124.7193.python-list@python.org>
 <87pn3ayvj2.fsf@hornfels.zedat.fu-berlin.de>
 <05df3a5f53b4d92a34f8399265a84b27f630da96.camel@anode.ca>
 <mailman.420.1608109951.7193.python-list@python.org>
 <87lfdyytwd.fsf@hornfels.zedat.fu-berlin.de>
 <CAPTjJmqZry5=wD-3GhQ87kHz-EKDJt5V9MiC=8R5pdDEqHidxw@mail.gmail.com>
 <09aee7aa-146c-1c7f-1d0e-b800d7f4eac5@stoneleaf.us>
 <rrlrc1$1mi$1@ciao.gmane.io>
Message-ID: <X99Vjud8s2sjw5aB@scrozzle>

On 2020-12-19 at 22:29:34 +0100,
Roel Schroeven <roel at roelschroeven.net> wrote:

> What could be useful in some use cases, I think, is a wrapper function
> that evaluates the function lazily:
> 
>     def dict_get_lazily(d, key, fnc, *args, **kwargs):
>         try:
>             return d[key]
>         except KeyError:
>             return fnc(*args, **kwargs)
> 
>     some_var = dict_get_lazily(d, 'spam', some_function, 31, 11)

There's no need to pass all those arguments through dict_get_lazily, and
the language already has a way to evaluate an expression lazily:

    def dict_get_lazily(d, key, f):
        try:
            return d[key]
        except KeyError:
            return f()

    some_var = dict_get_lazily(d, 'spam', lambda: some_function(31, 11))

So, beyond a cache (of which there are many variations and many
implementations for many use cases), what are the use cases for an
entire dictionary of lazily computed values?  And if my application has
to know when to access d['key'] directly and when to call
dict_get_lazily(d, 'key', f), then whom am I fooling by "hiding" the
lazy evaluation?  But if I always call dict_get_lazily when I access d,
then why do those two or three lines belong in the standard library
instead of my application or my private toolbox?

From rosuav at gmail.com  Sun Dec 20 09:10:30 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 21 Dec 2020 01:10:30 +1100
Subject: dict.get(key, default) evaluates default even if key exists
In-Reply-To: <X99Vjud8s2sjw5aB@scrozzle>
References: <87bleu18s9.fsf@hornfels.zedat.fu-berlin.de>
 <92ed36a3e1fe6a3d3aaf5c935da1dc75402b172b.camel@anode.ca>
 <mailman.419.1608108124.7193.python-list@python.org>
 <87pn3ayvj2.fsf@hornfels.zedat.fu-berlin.de>
 <05df3a5f53b4d92a34f8399265a84b27f630da96.camel@anode.ca>
 <mailman.420.1608109951.7193.python-list@python.org>
 <87lfdyytwd.fsf@hornfels.zedat.fu-berlin.de>
 <CAPTjJmqZry5=wD-3GhQ87kHz-EKDJt5V9MiC=8R5pdDEqHidxw@mail.gmail.com>
 <09aee7aa-146c-1c7f-1d0e-b800d7f4eac5@stoneleaf.us>
 <rrlrc1$1mi$1@ciao.gmane.io> <X99Vjud8s2sjw5aB@scrozzle>
Message-ID: <CAPTjJmrM+eU7DtQbubpUxynVkr_v4k+vMYoyDLJezkzVD-A6YA@mail.gmail.com>

On Mon, Dec 21, 2020 at 12:47 AM <2QdxY4RzWzUUiLuE at potatochowder.com> wrote:
>
> On 2020-12-19 at 22:29:34 +0100,
> Roel Schroeven <roel at roelschroeven.net> wrote:
>
> > What could be useful in some use cases, I think, is a wrapper function
> > that evaluates the function lazily:
> >
> >     def dict_get_lazily(d, key, fnc, *args, **kwargs):
> >         try:
> >             return d[key]
> >         except KeyError:
> >             return fnc(*args, **kwargs)
> >
> >     some_var = dict_get_lazily(d, 'spam', some_function, 31, 11)
>
> There's no need to pass all those arguments through dict_get_lazily, and
> the language already has a way to evaluate an expression lazily:
>
>     def dict_get_lazily(d, key, f):
>         try:
>             return d[key]
>         except KeyError:
>             return f()
>
>     some_var = dict_get_lazily(d, 'spam', lambda: some_function(31, 11))
>

class LazyDict(dict):
    def __missing__(self, key):
        # Pretend this is slow
        print("slow function called")
        return 31 + 11

d = LazyDict({
    'spam': 0,
    'ham': 1,
    'parrot': 2,
})
print(d['spam'])
print(d['eggs'])

Guaranteed to be called when and only when the key is missing. This
does imply a variant architecture in which the data structure itself
is aware of the calculations necessary to generate the data, so it may
not be appropriate to all situations, but it's clean, easy, and
efficient.

If you can't do this, I'd recommend using the try/except method, maybe
wrapped up in a function if you want to. In the case where the key is
found, the cost is one try block and one lookup - barely more than any
other option (for the record, a try block is pretty cheap in CPython,
and it's only costly when you hit an exception); and where it isn't
found, it's two lookups plus the cost of generating the default (and
we've already established that generating the default is expensive,
otherwise setdefault would be appropriate).

ChrisA

From cl at isbd.net  Sun Dec 20 11:02:53 2020
From: cl at isbd.net (Chris Green)
Date: Sun, 20 Dec 2020 16:02:53 +0000
Subject: How do you find what exceptions a class can throw?
References: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
 <exceptions-20201220155001@ram.dialup.fu-berlin.de>
Message-ID: <d694bh-118l.ln1@esprimo.zbmc.eu>

Stefan Ram <ram at zedat.fu-berlin.de> wrote:
> Chris Green <cl at isbd.net> writes:
> >I am using poplib.POP3_SSL() and I want to know what exceptions can be
> >thrown when I instantiate it.  Presumably it inherits them because
> >there's nothing much in the documentation page for poplib.POP3_SSL().
> 
>   Both Java and C++ have tried to introduce a static
>   declaration of exceptions IIRC, but IIRC this was less
>   popular as it led to problems.
> 
>   Ultimately, it is not possible to tell what exceptions 
>   a call might throw. In such a case, it may help to explain
>   to the newsgroup why this information is needed.
> 
So that, as is always advised, I can catch the specific exception
being thrown!

-- 
Chris Green
?

From 2QdxY4RzWzUUiLuE at potatochowder.com  Sun Dec 20 12:05:26 2020
From: 2QdxY4RzWzUUiLuE at potatochowder.com (2QdxY4RzWzUUiLuE at potatochowder.com)
Date: Sun, 20 Dec 2020 11:05:26 -0600
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <d694bh-118l.ln1@esprimo.zbmc.eu>
References: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
 <exceptions-20201220155001@ram.dialup.fu-berlin.de>
 <d694bh-118l.ln1@esprimo.zbmc.eu>
Message-ID: <X9+EVuoIqxybaLU+@scrozzle>

On 2020-12-20 at 16:02:53 +0000,
Regarding "Re: How do you find what exceptions a class can throw?,"
Chris Green <cl at isbd.net> wrote:

> Stefan Ram <ram at zedat.fu-berlin.de> wrote:
> > Chris Green <cl at isbd.net> writes:
> > >I am using poplib.POP3_SSL() and I want to know what exceptions can be
> > >thrown when I instantiate it.  Presumably it inherits them because
> > >there's nothing much in the documentation page for poplib.POP3_SSL().
> > 
> >   Both Java and C++ have tried to introduce a static
> >   declaration of exceptions IIRC, but IIRC this was less
> >   popular as it led to problems.
> > 
> >   Ultimately, it is not possible to tell what exceptions 
> >   a call might throw. In such a case, it may help to explain
> >   to the newsgroup why this information is needed.
> > 
> So that, as is always advised, I can catch the specific exception
> being thrown!

To the point:  what are you going to do with it once you catch it?

Are you prepared to handle every exception individually, or are you
fishing for exceptions that you think might be worth catching?

Remember, you get reporting (a traceback) and program cleanup and exit
for free.  What will catching an exception *add* to the user experience?

From julio at diegidio.name  Sun Dec 20 13:12:49 2020
From: julio at diegidio.name (Julio Di Egidio)
Date: Sun, 20 Dec 2020 10:12:49 -0800 (PST)
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <7uc4bh-q3gl.ln1@esprimo.zbmc.eu>
References: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
 <exceptions-20201220155001@ram.dialup.fu-berlin.de>
 <d694bh-118l.ln1@esprimo.zbmc.eu>
 <catching-20201220174646@ram.dialup.fu-berlin.de>
 <7uc4bh-q3gl.ln1@esprimo.zbmc.eu>
Message-ID: <30539a00-eb92-4a39-b113-8a2ba03b9437n@googlegroups.com>

On Sunday, 20 December 2020 at 18:18:26 UTC+1, Chris Green wrote:

> If I ignore the exception then the 
> program just exits, if I want the program to do something useful about 
> it (like try again) then I have to catch the specific exception as I 
> don't want to try again with other exceptions.

As other have hinted at, it's about handling, not so much about catching.

That said, the docs are your friend:

<https://docs.python.org/3.8/library/poplib.html#poplib.error_proto>
"exception poplib.error_proto -- Exception raised on any errors from this module (errors from socket module are not caught) [where "error_proto" I suppose stands for "protocol error"]. The reason for the exception is passed to the constructor as a string."  (It's also documented in the code docs...)

So that's one exception and the only explicit one (see below) specific to that module.  Then you should check the exceptions in the socket module:
<https://docs.python.org/3.8/library/socket.html#socket.error>

Incidentally, I have peeked at the source code for poplib, and the initializer of poplib.POP3_SSL also raises ValueError on invalid arguments.  I suppose similar should be expected from the socket module.  But these are the exceptions that typically are not handled: one has to validate input, so that, at that point, a ValueError, or a TypeError (or a KeyError, etc.) is rather a bug.  Anyway, this is another story...

Julio

From cl at isbd.net  Sun Dec 20 13:13:27 2020
From: cl at isbd.net (Chris Green)
Date: Sun, 20 Dec 2020 18:13:27 +0000
Subject: How do you find what exceptions a class can throw?
References: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
 <exceptions-20201220155001@ram.dialup.fu-berlin.de>
 <d694bh-118l.ln1@esprimo.zbmc.eu> <X9+EVuoIqxybaLU+@scrozzle>
 <mailman.480.1608483931.7193.python-list@python.org>
Message-ID: <7rg4bh-bvnl.ln1@esprimo.zbmc.eu>

2QdxY4RzWzUUiLuE at potatochowder.com wrote:
> On 2020-12-20 at 16:02:53 +0000,
> Regarding "Re: How do you find what exceptions a class can throw?,"
> Chris Green <cl at isbd.net> wrote:
> 
> > Stefan Ram <ram at zedat.fu-berlin.de> wrote:
> > > Chris Green <cl at isbd.net> writes:
> > > >I am using poplib.POP3_SSL() and I want to know what exceptions can be
> > > >thrown when I instantiate it.  Presumably it inherits them because
> > > >there's nothing much in the documentation page for poplib.POP3_SSL().
> > > 
> > >   Both Java and C++ have tried to introduce a static
> > >   declaration of exceptions IIRC, but IIRC this was less
> > >   popular as it led to problems.
> > > 
> > >   Ultimately, it is not possible to tell what exceptions 
> > >   a call might throw. In such a case, it may help to explain
> > >   to the newsgroup why this information is needed.
> > > 
> > So that, as is always advised, I can catch the specific exception
> > being thrown!
> 
> To the point:  what are you going to do with it once you catch it?
> 
> Are you prepared to handle every exception individually, or are you
> fishing for exceptions that you think might be worth catching?
> 
> Remember, you get reporting (a traceback) and program cleanup and exit
> for free.  What will catching an exception *add* to the user experience?

If it's a timeout exception I'm going to delay a little while and then
try again.  The timeout is probably because the server is busy.

If it's not a timeout then I'll (as you suggest) leave it to terminate
the program and report the error.

-- 
Chris Green
?

From Karsten.Hilbert at gmx.net  Sun Dec 20 13:34:51 2020
From: Karsten.Hilbert at gmx.net (Karsten Hilbert)
Date: Sun, 20 Dec 2020 19:34:51 +0100
Subject: Aw: Re: How do you find what exceptions a class can throw?
In-Reply-To: <7rg4bh-bvnl.ln1@esprimo.zbmc.eu>
References: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
 <exceptions-20201220155001@ram.dialup.fu-berlin.de>
 <d694bh-118l.ln1@esprimo.zbmc.eu> <X9+EVuoIqxybaLU+@scrozzle>
 <mailman.480.1608483931.7193.python-list@python.org>
 <7rg4bh-bvnl.ln1@esprimo.zbmc.eu>
Message-ID: <trinity-c7b4e446-66dd-4b6a-abf8-5445b5ee2f62-1608489291771@3c-app-gmx-bap51>

> > Remember, you get reporting (a traceback) and program cleanup and exit
> > for free.  What will catching an exception *add* to the user experience?
>
> If it's a timeout exception I'm going to delay a little while and then
> try again.  The timeout is probably because the server is busy.

So what you are looking for is the form of a potential
"timeout exception" (say, exception name) ?

Provoke one and have a look.

Then catch what you saw.

Karsten

From julio at diegidio.name  Sun Dec 20 13:46:25 2020
From: julio at diegidio.name (Julio Di Egidio)
Date: Sun, 20 Dec 2020 10:46:25 -0800 (PST)
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <mailman.481.1608489292.7193.python-list@python.org>
References: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
 <exceptions-20201220155001@ram.dialup.fu-berlin.de>
 <d694bh-118l.ln1@esprimo.zbmc.eu> <X9+EVuoIqxybaLU+@scrozzle>
 <mailman.480.1608483931.7193.python-list@python.org>
 <trinity-c7b4e446-66dd-4b6a-abf8-5445b5ee2f62-1608489291771@3c-app-gmx-bap51>
 <7rg4bh-bvnl.ln1@esprimo.zbmc.eu>
 <mailman.481.1608489292.7193.python-list@python.org>
Message-ID: <9a654681-64c8-4856-bafd-5984bd860f4an@googlegroups.com>

On Sunday, 20 December 2020 at 19:35:21 UTC+1, Karsten Hilbert wrote:

> > If it's a timeout exception I'm going to delay a little while and then 
> > try again. The timeout is probably because the server is busy.
> 
> So what you are looking for is the form of a potential 
> "timeout exception" (say, exception name) ? 
> 
> Provoke one and have a look. 
> 
> Then catch what you saw.

<https://docs.python.org/3.8/library/socket.html#socket.timeout>

Programmers don't guess...

HTH,

Julio

From grant.b.edwards at gmail.com  Sun Dec 20 13:25:40 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Sun, 20 Dec 2020 18:25:40 -0000 (UTC)
Subject: How do you find what exceptions a class can throw?
References: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
 <exceptions-20201220155001@ram.dialup.fu-berlin.de>
 <d694bh-118l.ln1@esprimo.zbmc.eu> <X9+EVuoIqxybaLU+@scrozzle>
Message-ID: <rro4v4$qcs$1@ciao.gmane.io>

On 2020-12-20, 2QdxY4RzWzUUiLuE at potatochowder.com <2QdxY4RzWzUUiLuE at potatochowder.com> wrote:
> Chris Green <cl at isbd.net> wrote:
>
>>>   Ultimately, it is not possible to tell what exceptions 
>>>   a call might throw.

While it may not be "ultimately possible", in practice it usually
is. Most libarary documentation lists exceptions thrown by fuctions
and explains what causes them.

>>>   In such a case, it may help to explain
>>>   to the newsgroup why this information is needed.
>>
>> So that, as is always advised, I can catch the specific exception
>> being thrown!
>
> To the point: what are you going to do with it once you catch it?

Seriously? You've never written code that handled an exception?

> Are you prepared to handle every exception individually,

Of course he isn't.

> or are you fishing for exceptions that you think might be worth
> catching?

You handle whatever exception(s) you expect, and let the others pass
up to higher levels. There are lots of cases where there may be one or
two exceptions that you want to handle.

> Remember, you get reporting (a traceback) and program cleanup and
> exit for free.  What will catching an exception *add* to the user
> experience?

Yes, if you can deal with it in such a way that normal execution of
the program (from the user's POV) continues. Exceptions aren't always
bugs and errors. Sometimes it's just an uncommon use-case that is
foreseen and dealt with.





From cl at isbd.net  Sun Dec 20 12:06:47 2020
From: cl at isbd.net (Chris Green)
Date: Sun, 20 Dec 2020 17:06:47 +0000
Subject: How do you find what exceptions a class can throw?
References: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
 <exceptions-20201220155001@ram.dialup.fu-berlin.de>
 <d694bh-118l.ln1@esprimo.zbmc.eu>
 <catching-20201220174646@ram.dialup.fu-berlin.de>
Message-ID: <7uc4bh-q3gl.ln1@esprimo.zbmc.eu>

Stefan Ram <ram at zedat.fu-berlin.de> wrote:
> Chris Green <cl at isbd.net> writes:
> >So that, as is always advised, I can catch the specific exception
> >being thrown!
> 
>   It usually is advisable to be more specific when catching
>   exceptions. The worst thing to do is surely a bare "except:"
>   which then ignores the exception.
> 
>   A general "except Exception:" is slightly better, since it
>   will not catch SystemExit and KeyboardInterrupt exceptions.
> 
>   According to me, you should only catch a specific exception
>   if you know better than your caller what to do in this case.
>   Otherwise just let it pass through to your caller.
> 
> 
"better than your caller"???  If I ignore the exception then the
program just exits, if I want the program to do something useful about
it (like try again) then I have to catch the specific exception as I
don't want to try again with other exceptions.

-- 
Chris Green
?

From Karsten.Hilbert at gmx.net  Sun Dec 20 13:53:42 2020
From: Karsten.Hilbert at gmx.net (Karsten Hilbert)
Date: Sun, 20 Dec 2020 19:53:42 +0100
Subject: Aw: Re: Re: How do you find what exceptions a class can throw?
In-Reply-To: <9a654681-64c8-4856-bafd-5984bd860f4an@googlegroups.com>
References: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
 <exceptions-20201220155001@ram.dialup.fu-berlin.de>
 <d694bh-118l.ln1@esprimo.zbmc.eu> <X9+EVuoIqxybaLU+@scrozzle>
 <mailman.480.1608483931.7193.python-list@python.org>
 <trinity-c7b4e446-66dd-4b6a-abf8-5445b5ee2f62-1608489291771@3c-app-gmx-bap51>
 <7rg4bh-bvnl.ln1@esprimo.zbmc.eu>
 <mailman.481.1608489292.7193.python-list@python.org>
 <9a654681-64c8-4856-bafd-5984bd860f4an@googlegroups.com>
Message-ID: <trinity-7d1b17e7-830d-45fe-a993-fafdb00d2bf9-1608490422070@3c-app-gmx-bap51>

> > So what you are looking for is the form of a potential
> > "timeout exception" (say, exception name) ?
> >
> > Provoke one and have a look.
> >
> > Then catch what you saw.
>
> <https://docs.python.org/3.8/library/socket.html#socket.timeout>
>
> Programmers don't guess...

I did not suggest guessing.

I suggested gathering scientific evidence by
running a controlled experiment.

Or should I say "Programmers don't trust..." ?

Karsten

From julio at diegidio.name  Sun Dec 20 14:14:24 2020
From: julio at diegidio.name (Julio Di Egidio)
Date: Sun, 20 Dec 2020 11:14:24 -0800 (PST)
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <mailman.483.1608490423.7193.python-list@python.org>
References: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
 <exceptions-20201220155001@ram.dialup.fu-berlin.de>
 <d694bh-118l.ln1@esprimo.zbmc.eu> <X9+EVuoIqxybaLU+@scrozzle>
 <mailman.480.1608483931.7193.python-list@python.org>
 <trinity-c7b4e446-66dd-4b6a-abf8-5445b5ee2f62-1608489291771@3c-app-gmx-bap51>
 <7rg4bh-bvnl.ln1@esprimo.zbmc.eu>
 <mailman.481.1608489292.7193.python-list@python.org>
 <trinity-7d1b17e7-830d-45fe-a993-fafdb00d2bf9-1608490422070@3c-app-gmx-bap51>
 <9a654681-64c8-4856-bafd-5984bd860f4an@googlegroups.com>
 <mailman.483.1608490423.7193.python-list@python.org>
Message-ID: <1ba0402d-e82a-460e-a7b0-fd24c35f29c8n@googlegroups.com>

On Sunday, 20 December 2020 at 19:54:08 UTC+1, Karsten Hilbert wrote:
> > > So what you are looking for is the form of a potential 
> > > "timeout exception" (say, exception name) ? 
> > > 
> > > Provoke one and have a look. 
> > > 
> > > Then catch what you saw. 
> > 
> > <https://docs.python.org/3.8/library/socket.html#socket.timeout> 
> > 
> > Programmers don't guess...
> 
> I did not suggest guessing. 

Yes, you did.  :)

> I suggested gathering scientific evidence by 
> running a controlled experiment.

Programming is not a science: in fact, computer science is a mathematics, and engineering is engineering.

Rather (speaking generally), the "trial and error" together with "not reading the docs" is a typical beginner's mistake.

> Or should I say "Programmers don't trust..." ? 

Trust me: it takes 100x getting anything done plus keep up with your prayers, and it takes 100^100x learning anything solid, as in just forget about it.  Indeed, consider that we are rather going to the formal verification of programs, software, and even hardware...

Julio

From Karsten.Hilbert at gmx.net  Sun Dec 20 14:34:03 2020
From: Karsten.Hilbert at gmx.net (Karsten Hilbert)
Date: Sun, 20 Dec 2020 20:34:03 +0100
Subject: Aw: Re: Re: Re: How do you find what exceptions a class can throw?
In-Reply-To: <1ba0402d-e82a-460e-a7b0-fd24c35f29c8n@googlegroups.com>
References: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
 <exceptions-20201220155001@ram.dialup.fu-berlin.de>
 <d694bh-118l.ln1@esprimo.zbmc.eu> <X9+EVuoIqxybaLU+@scrozzle>
 <mailman.480.1608483931.7193.python-list@python.org>
 <trinity-c7b4e446-66dd-4b6a-abf8-5445b5ee2f62-1608489291771@3c-app-gmx-bap51>
 <7rg4bh-bvnl.ln1@esprimo.zbmc.eu>
 <mailman.481.1608489292.7193.python-list@python.org>
 <trinity-7d1b17e7-830d-45fe-a993-fafdb00d2bf9-1608490422070@3c-app-gmx-bap51>
 <9a654681-64c8-4856-bafd-5984bd860f4an@googlegroups.com>
 <mailman.483.1608490423.7193.python-list@python.org>
 <1ba0402d-e82a-460e-a7b0-fd24c35f29c8n@googlegroups.com>
Message-ID: <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>

> Trust me: it takes 100x getting anything done plus keep up with your prayers, and it takes 100^100x learning anything solid, as in just forget about it.  Indeed, consider that we are rather going to the formal verification of programs, software, and even hardware...

I sincerly wish you that your hope becomes reality within your lifetime.

Karsten

From tanto at non.va.invalid  Sun Dec 20 15:00:19 2020
From: tanto at non.va.invalid (danilob)
Date: Sun, 20 Dec 2020 21:00:19 +0100
Subject: list() strange behaviour
Message-ID: <rroagh$qu7$1@gioia.aioe.org>

Hi,
I'm an absolute beginner in Python (and in English too ;-)
Running this code:


--------------
# Python 3.9.0

a = [[1, 2, 0, 3, 0],
      [0, 4, 5, 0, 6],
      [7, 0, 8, 0, 9],
      [2, 3, 0, 0, 1],
      [0, 0, 1, 8, 0]]


b = ((x[0] for x in a))

print(list(b))
print(list(b))
---------------


I get this output:

[1, 0, 7, 2, 0]
[]


I don't know why the second print() output shows an empty list.
Is it possible that the first print() call might have changed the value 
of "b"?

Thank you in advance.

From 2QdxY4RzWzUUiLuE at potatochowder.com  Sun Dec 20 15:49:08 2020
From: 2QdxY4RzWzUUiLuE at potatochowder.com (2QdxY4RzWzUUiLuE at potatochowder.com)
Date: Sun, 20 Dec 2020 14:49:08 -0600
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <rro4v4$qcs$1@ciao.gmane.io>
References: <5ni3bh-r5rj.ln1@esprimo.zbmc.eu>
 <exceptions-20201220155001@ram.dialup.fu-berlin.de>
 <d694bh-118l.ln1@esprimo.zbmc.eu> <X9+EVuoIqxybaLU+@scrozzle>
 <rro4v4$qcs$1@ciao.gmane.io>
Message-ID: <X9+4xBLDqf0ocepc@scrozzle>

On 2020-12-20 at 18:25:40 -0000,
Grant Edwards <grant.b.edwards at gmail.com> wrote:

> On 2020-12-20, 2QdxY4RzWzUUiLuE at potatochowder.com <2QdxY4RzWzUUiLuE at potatochowder.com> wrote:
> > Chris Green <cl at isbd.net> wrote:
> >
> >>>   Ultimately, it is not possible to tell what exceptions 
> >>>   a call might throw.
> 
> While it may not be "ultimately possible", in practice it usually
> is. Most libarary documentation lists exceptions thrown by fuctions
> and explains what causes them.
> 
> >>>   In such a case, it may help to explain
> >>>   to the newsgroup why this information is needed.
> >>
> >> So that, as is always advised, I can catch the specific exception
> >> being thrown!
> >
> > To the point: what are you going to do with it once you catch it?
> 
> Seriously? You've never written code that handled an exception?

No.  Of course I've written code that catches exceptions.

Have you ever written code that ignored an exception, explicitly or
implicitly?  Of course you have.

My point was to get the OP to think about *handling* exceptions, not
just catching them because a library function throws them, or trying to
deal with everything that might happen in the future.

> > Are you prepared to handle every exception individually,
> 
> Of course he isn't.

How do we know that?

> > or are you fishing for exceptions that you think might be worth
> > catching?
> 
> You handle whatever exception(s) you expect, and let the others pass
> up to higher levels. There are lots of cases where there may be one or
> two exceptions that you want to handle.

Subsequent emails indicate that Chris Green does as well, but it took a
while to get there (or perhaps I just misunderstood all those vague
references to catching exceptions).

> > Remember, you get reporting (a traceback) and program cleanup and
> > exit for free.  What will catching an exception *add* to the user
> > experience?
> 
> Yes, if you can deal with it in such a way that normal execution of
> the program (from the user's POV) continues. Exceptions aren't always
> bugs and errors. Sometimes it's just an uncommon use-case that is
> foreseen and dealt with.

Agreed.  Some programs recover from and continue under (for their own
definitions of "recover" and "continue") horrendous conditions, other
programs dump a traceback and let a user/operator/customer deal with it.
Chris Green gave little or no indication of expectations or desires.

From python.list at tim.thechases.com  Sun Dec 20 15:38:47 2020
From: python.list at tim.thechases.com (Tim Chase)
Date: Sun, 20 Dec 2020 14:38:47 -0600
Subject: list() strange behaviour
In-Reply-To: <rroagh$qu7$1@gioia.aioe.org>
References: <rroagh$qu7$1@gioia.aioe.org>
Message-ID: <20201220143847.1ff747ea@bigbox.attlocal.net>

On 2020-12-20 21:00, danilob wrote:
> b = ((x[0] for x in a))

here you create a generator

> print(list(b))
> [1, 0, 7, 2, 0]

and then you consume all the things it generates here which means
that when you go to do this a second time

> print(list(b))

the generator is already empty/exhausted so there's nothing more to
yield, giving you the empty result that you got:

> []


If you want to do this, convert it to a list once:

 >>> c = list(b)

or use a list-comprehension instead creating a generator

 >>> c = [x[0] for x in a]

and then print that resulting list:

 >>> print(c)
 >>> print(c)

-tkc




From cs at cskk.id.au  Sun Dec 20 16:09:47 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Mon, 21 Dec 2020 08:09:47 +1100
Subject: list() strange behaviour
In-Reply-To: <rroagh$qu7$1@gioia.aioe.org>
References: <rroagh$qu7$1@gioia.aioe.org>
Message-ID: <20201220210947.GA66939@cskk.homeip.net>

On 20Dec2020 21:00, danilob <tanto at non.va.invalid> wrote:
>I'm an absolute beginner in Python (and in English too ;-)

Well your English is far better than my very poor second language.

>Running this code:
>--------------
># Python 3.9.0
>
>a = [[1, 2, 0, 3, 0],
>     [0, 4, 5, 0, 6],
>     [7, 0, 8, 0, 9],
>     [2, 3, 0, 0, 1],
>     [0, 0, 1, 8, 0]]

This is a list of lists.

>b = ((x[0] for x in a))

This is a generator comprehension, and _not_ a list. Explainations 
below.

>print(list(b))
>print(list(b))
>---------------
>I get this output:
>
>[1, 0, 7, 2, 0]

As you expect.

>[]

As a surprise.

>I don't know why the second print() output shows an empty list.
>Is it possible that the first print() call might have changed the value 
>of "b"?

It hasn't but, it has changed its state. Let me explain.

In Python there are 2 visually similar list-like comprehensions:

This is a _list_ comprehension (note the surrounding square brackets):

    [ x for x in range(5) ]

It genuinely constructs a list containing:

    [ 0, 1, 2, 3, 4 ]

and would behave as you expect in print().

By contrast, this is a generator comprehension (note the round 
brackets):

    ( x for x in range(5) )

This is a "lazy" construct, and is like writing a generator function:

    def g():
        for x in range(5):
            yield x

It is a little iterable which _counts_ from 0 through 4 inclusive and 
yields each value as requested.

Try putting a:

    print(b)

before your other print calls. It will not show a list.

So, what is happening?

    b = ((x[0] for x in a))

This makes a generator comprehension. The outermost brackets are 
redundant, by the way, and can be discarded:

    b = (x[0] for x in a)

And does this (using my simpler example range(5)):

    >>> b=(x for x in range(5))
    >>> b
    <generator object <genexpr> at 0x10539e120>

When you make a list from that:

    >>> L = list(b)
    >>> L
    [0, 1, 2, 3, 4]

the generator _runs_ and emits the values to be used in the list. If you 
make another list:

    >>> L = list(b)
    >>> L
    []

The generator has finished. Using it again produces no values, and so 
list() constructs an empty list.

That is what is happening in your print statements.

If, instead, you had gone:

    b = [x[0] for x in a]

Then "b" would be an actual list (a sequence of values stored in memory) 
and your prints would have done what you expect.

Python has several "lazy" operations available, which do not do the 
entire computation when they are defined; instead they give you a 
"generator" which performs the computation incrementally, running until 
the next value is found - when the user asks for the next value, _then_ 
the generator runs until that value is obtained and "yield"ed.

Supposing your array "a" were extremely large, or perhaps in some way 
stored in a database instead of in memory. It might be expensive or very 
slow to get _all_ the values. A generator lets you get values as they 
are required.

A generator expression like this:

    b = ( x for x in range(5) )

counts from 0 through 4 inclusively (or 0 through 5, excluding 5, which 
is how ranges egenrally work in Python) when asks. As a function it 
might look like this:

    def b():
        for x in range(5)
            yield x

When you call "list(b)" the list constructor collects values from 
"iter(b)", which iterates over "b". Like this, written longhand:

    L = []
    for value in b:
        L.append(b)

Written even longer:

    L = []
    b_values = iter(b)
    while True:
        try:
            value = next(b_values)
        except Stopiteration:
            break
        L.append(value)

which more clearly shows a call to "next()" to run the iterator b_values 
once, until it yields a value.

The Python for-statement is a builtin convenient way to write the 
while-loop above - it iterates over any iterable like "b".

Cheers,
Cameron Simpson <cs at cskk.id.au>

From cs at cskk.id.au  Sun Dec 20 17:15:32 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Mon, 21 Dec 2020 09:15:32 +1100
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>
References: <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>
Message-ID: <20201220221532.GA14120@cskk.homeip.net>

On 20Dec2020 20:34, Karsten Hilbert <Karsten.Hilbert at gmx.net> wrote:
>> Trust me: it takes 100x getting anything done plus keep up with your prayers, and it takes 100^100x learning anything solid, as in just forget about it.  Indeed, consider that we are rather going to the formal verification of programs, software, and even hardware...
>
>I sincerly wish you that your hope becomes reality within your 
>lifetime.

Aye, since "we are rather going to the formal verification of programs, 
software, and even hardware" was true when I was at university. In the 
1980s and 1990s.

Gathering evidence is indeed part of science, and computer science is 
indeed mathematics, but alas programmering is just a craft and software 
engineering often ... isn't.

Anyway, I would hope we're all for more rigour rather than less.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From julio at diegidio.name  Sun Dec 20 21:06:02 2020
From: julio at diegidio.name (Julio Di Egidio)
Date: Sun, 20 Dec 2020 18:06:02 -0800 (PST)
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <mailman.488.1608502543.7193.python-list@python.org>
References: <20201220221532.GA14120@cskk.homeip.net>
 <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>
 <mailman.488.1608502543.7193.python-list@python.org>
Message-ID: <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>

On Sunday, 20 December 2020 at 23:16:10 UTC+1, cameron... at gmail.com wrote:
> On 20Dec2020 20:34, Karsten Hilbert <Karsten... at gmx.net> wrote: 
> >> Trust me: it takes 100x getting anything done plus keep up with your prayers, and it takes 100^100x learning anything solid, as in just forget about it. Indeed, consider that we are rather going to the formal verification of programs, software, and even hardware... 
> > 
> >I sincerly wish you that your hope becomes reality within your 
> >lifetime.
> 
> Aye, since "we are rather going to the formal verification of programs, 
> software, and even hardware" was true when I was at university. In the 
> 1980s and 1990s. 

You could have taken the chance to pay attention, as after 30 years of fake agility, lies over the very state of the art, and of course the chronic spectacular failures, the defamation game and the misery of an entire industry, we are eventually getting back to where we were.  And, while we are still quite far from an end-to-end integrated experience, by now, Dec 2020, it is already the case that there are enough systems, libraries/components and of course the underlying theory that for the practitioner (i.e. the professional in the field) the problem at the moment is rather which ones to commit to (i.e. invest money and time into).

> Gathering evidence is indeed part of science, and computer science is 
> indeed mathematics, but alas programmering is just a craft and software 
> engineering often ... isn't. 

Programming is a *discipline*, while you keep echoing cheap and vile marketing nonsense.

> Anyway, I would hope we're all for more rigour rather than less. 

I am sure you do, rigour mortis eventually...

EOD.

Julio

From ethan at stoneleaf.us  Sun Dec 20 21:26:35 2020
From: ethan at stoneleaf.us (Ethan Furman)
Date: Sun, 20 Dec 2020 18:26:35 -0800
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>
References: <20201220221532.GA14120@cskk.homeip.net>
 <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>
 <mailman.488.1608502543.7193.python-list@python.org>
 <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>
Message-ID: <8796dfbb-309f-36d4-6e31-530f119b6aff@stoneleaf.us>

On 12/20/20 6:06 PM, Julio Di Egidio wrote:

> You could have taken the chance to pay attention

> Programming is a *discipline*, while you keep echoing cheap and vile marketing nonsense.

> I am sure you do, rigour mortis eventually...

Mean-spirited and hostile messages are not welcome on this list.

--
~Ethan~

From rosuav at gmail.com  Sun Dec 20 21:35:05 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 21 Dec 2020 13:35:05 +1100
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>
References: <20201220221532.GA14120@cskk.homeip.net>
 <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>
 <mailman.488.1608502543.7193.python-list@python.org>
 <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>
Message-ID: <CAPTjJmoEQURYxBZ_G-9BRtFhusCbXBVTy8NTAAcMCcTvka0LBQ@mail.gmail.com>

On Mon, Dec 21, 2020 at 1:11 PM Julio Di Egidio <julio at diegidio.name> wrote:
> > Gathering evidence is indeed part of science, and computer science is
> > indeed mathematics, but alas programmering is just a craft and software
> > engineering often ... isn't.
>
> Programming is a *discipline*

It's a discipline, a science, AND an art. I love programming :)

ChrisA

From avigross at verizon.net  Sun Dec 20 21:46:48 2020
From: avigross at verizon.net (Avi Gross)
Date: Sun, 20 Dec 2020 21:46:48 -0500
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>
References: <20201220221532.GA14120@cskk.homeip.net>
 <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>
 <mailman.488.1608502543.7193.python-list@python.org>
 <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>
Message-ID: <0ad701d6d743$87c42e10$974c8a30$@verizon.net>

The original question sounded like someone was asking what errors might be
thrown for a routine they wrote that used other components that might
directly throw exceptions or called yet others, ad nauseum.

Some have questioned the purpose.

I can well imagine that if such info was available, you could construct a
data structure such as a graph and trace every possible error  that could
propagate back. But I am not so sure it is that simple.

Some of the intervening functions will quite possibly deal with those
errors. If a routine downstream already knows a further function might
divide by zero, it may arrange to capture that exception and deal with it.
So it will not likely propagate up from that source, albeit a second path
may also possibly let it propagate through on another such bad calculation
that does not deal with it.. 

Further, some programs have code that checks the environment and may use
different functions/methods if on one kind of machine or OS or version of
python than another. Ideally you would need to know the profile for the
build you are on. And with interpreted languages, some are not so much built
ahead of time as assembled as they go. Loading an alternate module or
library with functions having the same names, may bring in a very different
profile of possible exceptions.

And what if your function is later used by others and they do not know you
added code to intercept all possible interruptions and chose how to deal
with them and they write code hoping to intercept something that then never
arrives. Things may fail differently than expected. Some nice programming
tricks that depend on it failing sometimes, may no longer work as expected.

What exactly is the right way to deal with each interrupt? Choices range
from ignoring them while squelching them, to passing them along relatively
unchanged, perhaps logging what came by, raising a different exception,
perhaps your own new variety, or just halting everything. 

Any time some deeper software is changed, as for a bug fix, they may change
the profile of propagated errors. A routine that once worried about running
out of memory may instead change to only working on memory pre-allocated in
large blocks yet leave in the code that would throw an exception if it is
ever reached. It may be it can now never happen but yet you might still be
on the lookout for it, especially if the documentation does not change or
you do not read it each and every time.

I also wonder at the complexity of the code needed. If a given error in a
dozen places can generate the same exception, can you tell them apart so
each has an appropriate solution or do you lump them together? Can you
replace a function with a few lines of code with thousands of lines of
just-in-case code and remain viable if every function does this and you have
giant programs that use lots of CPU and memory?

I would say it is a more laudable goal for each function to publish what
interrupts they do NOT handle that might come through and perhaps why. Any
they claim to handle make it moot what happens further along the stream if
done right. Bulletproofing even then may seem harmless, of course. I have
had cases where I intercepted ALL errors when a rare case broke code I used
that  I did not write. I got an odd error  maybe once every million times
running on random simulated data and I just wanted to throw that result away
and keep a subset of those that worked and converged and passed some
post.tests. It did not matter to me why it failed, just that it not be
allowed to crash the program entirely. Trying to deal with every possible
exception would have been overkill.

So, I do sympathize with a wish to be able to decide what errors might arise
and be able to decide if having your code deal with it makes sense. I just
suggest whatever you do in the general case may not be optimal. It may do
too much and yet allow problems to seep through.






From 2QdxY4RzWzUUiLuE at potatochowder.com  Sun Dec 20 22:24:00 2020
From: 2QdxY4RzWzUUiLuE at potatochowder.com (2QdxY4RzWzUUiLuE at potatochowder.com)
Date: Sun, 20 Dec 2020 21:24:00 -0600
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <0ad701d6d743$87c42e10$974c8a30$@verizon.net>
References: <20201220221532.GA14120@cskk.homeip.net>
 <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>
 <mailman.488.1608502543.7193.python-list@python.org>
 <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>
 <0ad701d6d743$87c42e10$974c8a30$@verizon.net>
Message-ID: <X+AVUGDugYlykhE7@scrozzle>

On 2020-12-20 at 21:46:48 -0500,
Avi Gross via Python-list <python-list at python.org> wrote:

[...]

> I would say it is a more laudable goal for each function to publish
> what interrupts they do NOT handle that might come through and perhaps
> why ...

I'm not disagreeing.  Documenting important decisions and the reasons
behind them is amongst the best of Best Practices.

That said, either way, it's the same thing.  If A calls B, and B calls
C, and B claims *not* to handle exceptions X and Y, then A has to track
down everything else that might come from C, and we're right back to
square one (or square zero, but I digress).

> So, I do sympathize with a wish to be able to decide what errors might
> arise and be able to decide if having your code deal with it makes
> sense. I just suggest whatever you do in the general case may not be
> optimal. It may do too much and yet allow problems to seep through.

Excellent point, and well said.

So how do we eliminate the general case?  ;-)

From cs at cskk.id.au  Sun Dec 20 22:42:58 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Mon, 21 Dec 2020 14:42:58 +1100
Subject: list() strange behaviour
In-Reply-To: <20201220210947.GA66939@cskk.homeip.net>
References: <20201220210947.GA66939@cskk.homeip.net>
Message-ID: <20201221034258.GA64908@cskk.homeip.net>

On 21Dec2020 08:09, Cameron Simpson <cs at cskk.id.au> wrote:
>>b = ((x[0] for x in a))
>
>This is a generator comprehension, and _not_ a list.

I should amend this: a "generator _expression_", not comprehension. A 
"generator comprehension" is not a thing.

Apologies,
Cameron Simpson <cs at cskk.id.au>

From cl at isbd.net  Mon Dec 21 04:06:02 2020
From: cl at isbd.net (Chris Green)
Date: Mon, 21 Dec 2020 09:06:02 +0000
Subject: How do you find what exceptions a class can throw?
References: <20201220221532.GA14120@cskk.homeip.net>
 <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>
 <mailman.488.1608502543.7193.python-list@python.org>
 <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>
 <0ad701d6d743$87c42e10$974c8a30$@verizon.net>
 <mailman.492.1608518814.7193.python-list@python.org>
Message-ID: <q456bh-mi1p.ln1@esprimo.zbmc.eu>

Avi Gross <avigross at verizon.net> wrote:
> The original question sounded like someone was asking what errors might be
> thrown for a routine they wrote that used other components that might
> directly throw exceptions or called yet others, ad nauseum.
> 
OP here.  The original question was because I wanted to trap timout
errors when connectiing to a POP3 server in a very simple little
program that collects mail and runs it through a filter before
delivering it.

Thus I simply needed to know what the 'name' of the exception was so I
could trap only timeouts.  Timeout errors are (probably) 'soft' errors
which merit a retry, most other errors when trying to connect to a POP
server would be unrecoverable (POP syntax, wrong name, wrong password,
etc.).

It didn't seem such a difficult question when I asked it! :-)

-- 
Chris Green
?

From larry.martell at gmail.com  Mon Dec 21 08:30:03 2020
From: larry.martell at gmail.com (Larry Martell)
Date: Mon, 21 Dec 2020 08:30:03 -0500
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <CAPTjJmoEQURYxBZ_G-9BRtFhusCbXBVTy8NTAAcMCcTvka0LBQ@mail.gmail.com>
References: <20201220221532.GA14120@cskk.homeip.net>
 <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>
 <mailman.488.1608502543.7193.python-list@python.org>
 <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>
 <CAPTjJmoEQURYxBZ_G-9BRtFhusCbXBVTy8NTAAcMCcTvka0LBQ@mail.gmail.com>
Message-ID: <CACwCsY4vZVKuh5TZyEMK9WxerMr6DhM8Ke_57_V-PQE4aiNZuA@mail.gmail.com>

On Sun, Dec 20, 2020 at 9:36 PM Chris Angelico <rosuav at gmail.com> wrote:
>
> On Mon, Dec 21, 2020 at 1:11 PM Julio Di Egidio <julio at diegidio.name> wrote:
> > > Gathering evidence is indeed part of science, and computer science is
> > > indeed mathematics, but alas programmering is just a craft and software
> > > engineering often ... isn't.
> >
> > Programming is a *discipline*
>
> It's a discipline, a science, AND an art. I love programming :)


I love it too. But I think it?s a craft not an art. I think of art as
totally unconstrained, and a craft as having to functionally work.

I really like this quote: "Debugging is like being the detective in a
crime movie where you are also the murderer." - Filipe Fortes

From rosuav at gmail.com  Mon Dec 21 08:58:30 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 22 Dec 2020 00:58:30 +1100
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <CACwCsY4vZVKuh5TZyEMK9WxerMr6DhM8Ke_57_V-PQE4aiNZuA@mail.gmail.com>
References: <20201220221532.GA14120@cskk.homeip.net>
 <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>
 <mailman.488.1608502543.7193.python-list@python.org>
 <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>
 <CAPTjJmoEQURYxBZ_G-9BRtFhusCbXBVTy8NTAAcMCcTvka0LBQ@mail.gmail.com>
 <CACwCsY4vZVKuh5TZyEMK9WxerMr6DhM8Ke_57_V-PQE4aiNZuA@mail.gmail.com>
Message-ID: <CAPTjJmr8Ostzu3HW-cY_Zraos35ngHBwkx0si_9NUwT-wdUPeA@mail.gmail.com>

On Tue, Dec 22, 2020 at 12:32 AM Larry Martell <larry.martell at gmail.com> wrote:
>
> On Sun, Dec 20, 2020 at 9:36 PM Chris Angelico <rosuav at gmail.com> wrote:
> >
> > On Mon, Dec 21, 2020 at 1:11 PM Julio Di Egidio <julio at diegidio.name> wrote:
> > > > Gathering evidence is indeed part of science, and computer science is
> > > > indeed mathematics, but alas programmering is just a craft and software
> > > > engineering often ... isn't.
> > >
> > > Programming is a *discipline*
> >
> > It's a discipline, a science, AND an art. I love programming :)
>
>
> I love it too. But I think it?s a craft not an art. I think of art as
> totally unconstrained, and a craft as having to functionally work.

Hmmmmmmmmmmm...

*looks at some of his recent code*

This stuff has to work?!? I've been doing it all wrong...

> I really like this quote: "Debugging is like being the detective in a
> crime movie where you are also the murderer." - Filipe Fortes

Oh yes, absolutely. Only, you don't even know if a murder's been
committed yet...

ChrisA

From sersadaka1 at outlook.com  Mon Dec 21 11:01:55 2020
From: sersadaka1 at outlook.com (Sadaka Technology)
Date: Mon, 21 Dec 2020 08:01:55 -0800 (PST)
Subject: Python pyrebase user auth
Message-ID: <89009d57-1c2f-4eb6-b8f0-7e95167ea87dn@googlegroups.com>

Hello guys, how can I get user auth refresh token  and local id ?

From lukasz at langa.pl  Mon Dec 21 14:42:03 2020
From: lukasz at langa.pl (=?utf-8?Q?=C5=81ukasz_Langa?=)
Date: Mon, 21 Dec 2020 20:42:03 +0100
Subject: [RELEASE] Python 3.8.7 is now available
Message-ID: <9E5D7EDC-1A52-4962-ABD8-F01AF62C4CF0@langa.pl>

Python 3.8.7 is the seventh maintenance release of Python 3.8. Go get it here:

https://www.python.org/downloads/release/python-387/ <https://www.python.org/downloads/release/python-387/>
Note: this is a bugfix release for the 3.8 series which was superseded by Python 3.9, currently the latest feature release series of Python 3. You can find the latest release of 3.9.x here <https://www.python.org/downloads/>.

Maintenance releases for the 3.8 series will continue at regular bi-monthly intervals, with 3.8.8 planned for February 2021.

macOS 11 Big Sur not fully supported

Python 3.8.7 is not yet fully supported on macOS 11 Big Sur. It will install on macOS 11 Big Sur and will run on Apple Silicon Macs using Rosetta 2 translation. However, a few features do not work correctly, most noticeably those involving searching for system libraries (vs user libraries) such as ctypes.util.find_library() and in Distutils. This limitation affects both Apple Silicon and Intel processors. We are looking into improving the situation for Python 3.8.8.

Python 3.9.1 <https://www.python.org/downloads/release/python-391/> provides full support for Big Sur and Apple Silicon Macs, including building natively on Apple Silicon Macs and support for universal2 binaries.

What?s new?

The Python 3.8 series contains many new features and optimizations over 3.7. See the ?What?s New in Python 3.8 <https://docs.python.org/3.8/whatsnew/3.8.html>? document for more information about features included in the 3.8 series.

Detailed information about all changes made in version 3.8.7 specifically can be found in its change log <https://docs.python.org/release/3.8.7/whatsnew/changelog.html#python-3-8-7>. Note that compared to 3.8.6 this release also contains all changes present in 3.8.7rc1.

We hope you enjoy Python 3.8!

Thanks to all of the many volunteers who help make Python Development and these releases possible! Please consider supporting our efforts by volunteering yourself or through organization contributions to the Python Software Foundation.

Your friendly release team,
Ned Deily @nad <https://discuss.python.org/u/nad>
Steve Dower @steve.dower <https://discuss.python.org/u/steve.dower>
?ukasz Langa @ambv <https://discuss.python.org/u/ambv>

From grant.b.edwards at gmail.com  Sun Dec 20 22:50:32 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Mon, 21 Dec 2020 03:50:32 -0000 (UTC)
Subject: How do you find what exceptions a class can throw?
References: <20201220221532.GA14120@cskk.homeip.net>
 <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>
 <mailman.488.1608502543.7193.python-list@python.org>
 <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>
 <CAPTjJmoEQURYxBZ_G-9BRtFhusCbXBVTy8NTAAcMCcTvka0LBQ@mail.gmail.com>
Message-ID: <rrp628$erp$1@ciao.gmane.io>

On 2020-12-21, Chris Angelico <rosuav at gmail.com> wrote:
> On Mon, Dec 21, 2020 at 1:11 PM Julio Di Egidio <julio at diegidio.name> wrote:
>> > Gathering evidence is indeed part of science, and computer science is
>> > indeed mathematics, but alas programmering is just a craft and software
>> > engineering often ... isn't.
>>
>> Programming is a *discipline*
>
> It's a discipline, a science, AND an art.

And a craft.

And a dessert topping!



From peter at p-walker.co.uk  Mon Dec 21 06:23:39 2020
From: peter at p-walker.co.uk (peter walker)
Date: Mon, 21 Dec 2020 11:23:39 -0000
Subject: Problem running Pygame Zero
Message-ID: <011501d6d78b$bbcf2870$336d7950$@p-walker.co.uk>

Hi

I hope you can help. I am trying to use pygame zero (working with my 10 year
old grandson) but it won't run anything ( I did have it running for a little
while now nothing).

Below are the results of:

1.	Installing pygame zero
2.	Running a listing (whatever I run I get the same result).
3.	Listing of the file I am running

I have tried more than one version of Python and get the same results except
on Python 3.9.0 and .1 when pygame won't even install.

Please give me some help, I don't know how to proceed.

Thanking you in advance.

Peter Walker

 

PS C:\Users\Peter\Dropbox\My PC (Peter-Desktop)\Documents\escape> pip
install pgzero

Collecting pgzero

  Using cached pgzero-1.2-py3-none-any.whl (69 kB)

Requirement already satisfied: pygame<2.0,>=1.9.2 in
c:\users\peter\appdata\local\programs\python\python38\lib\site-packages
(from pgzero) (1.9.6)

Requirement already satisfied: numpy in
c:\users\peter\appdata\local\programs\python\python38\lib\site-packages
(from pgzero) (1.19.4)

Installing collected packages: pgzero

Successfully installed pgzero-1.2

PS C:\Users\Peter\Dropbox\My PC (Peter-Desktop)\Documents\escape>

 

PS C:\Users\Peter\Dropbox\My PC (Peter-Desktop)\Documents\escape> pgzrun
test.py

** On entry to DGEBAL parameter number  3 had an illegal value

** On entry to DGEHRD  parameter number  2 had an illegal value

** On entry to DORGHR DORGQR parameter number  2 had an illegal value

** On entry to DHSEQR parameter number  4 had an illegal value

Traceback (most recent call last):

  File "c:\users\peter\appdata\local\programs\python\python38\lib\runpy.py",
line 194, in _run_module_as_main

    return _run_code(code, main_globals, None,

  File "c:\users\peter\appdata\local\programs\python\python38\lib\runpy.py",
line 87, in _run_code

    exec(code, run_globals)

  File
"C:\Users\Peter\AppData\Local\Programs\Python\Python38\Scripts\pgzrun.exe\__
main__.py", line 4, in <module>

  File
"c:\users\peter\appdata\local\programs\python\python38\lib\site-packages\pgz
ero\runner.py", line 1, in <module>

    import pygame

  File
"c:\users\peter\appdata\local\programs\python\python38\lib\site-packages\pyg
ame\__init__.py", line 343, in <module>

    import pygame.surfarray

  File
"c:\users\peter\appdata\local\programs\python\python38\lib\site-packages\pyg
ame\surfarray.py", line 64, in <module>

    import pygame._numpysurfarray as numpysf

  File
"c:\users\peter\appdata\local\programs\python\python38\lib\site-packages\pyg
ame\_numpysurfarray.py", line 51, in <module>

    import numpy

  File
"c:\users\peter\appdata\local\programs\python\python38\lib\site-packages\num
py\__init__.py", line 305, in <module>

    _win_os_check()

  File
"c:\users\peter\appdata\local\programs\python\python38\lib\site-packages\num
py\__init__.py", line 302, in _win_os_check

    raise RuntimeError(msg.format(__file__)) from None

RuntimeError: The current Numpy installation
('c:\\users\\peter\\appdata\\local\\programs\\python\\python38\\lib\\site-pa
ckages\\numpy\\__init__.py') fails to pass a sanity check due to a bug in
the windows runtime. See this issue for more information:
https://tinyurl.com/y3dm3h86

PS C:\Users\Peter\Dropbox\My PC (Peter-Desktop)\Documents\escape>

 

Test.py

print("Hello")

 

 


From tjreedy at udel.edu  Mon Dec 21 14:35:27 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 21 Dec 2020 14:35:27 -0500
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <q456bh-mi1p.ln1@esprimo.zbmc.eu>
References: <20201220221532.GA14120@cskk.homeip.net>
 <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>
 <mailman.488.1608502543.7193.python-list@python.org>
 <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>
 <0ad701d6d743$87c42e10$974c8a30$@verizon.net>
 <mailman.492.1608518814.7193.python-list@python.org>
 <q456bh-mi1p.ln1@esprimo.zbmc.eu>
Message-ID: <rrqte0$11fm$1@ciao.gmane.io>

On 12/21/2020 4:06 AM, Chris Green wrote:
> Avi Gross <avigross at verizon.net> wrote:
>> The original question sounded like someone was asking what errors might be
>> thrown for a routine they wrote that used other components that might
>> directly throw exceptions or called yet others, ad nauseum.
>>
> OP here.  The original question was because I wanted to trap timout
> errors when connectiing to a POP3 server in a very simple little
> program that collects mail and runs it through a filter before
> delivering it.


> Thus I simply needed to know what the 'name' of the exception was so I
> could trap only timeouts.
...
 > It didn't seem such a difficult question when I asked it! :-)


Please acknowledge that this is *not* what you asked.

"I am using poplib.POP3_SSL() and I want to know what exceptions can be 
thrown when I instantiate it. "

If you had just asked "What is the name of a possible timeout error" 
someone would have answered just that.

-- 
Terry Jan Reedy


From vincent.vande.vyvre at telenet.be  Mon Dec 21 05:11:53 2020
From: vincent.vande.vyvre at telenet.be (Vincent Vande Vyvre)
Date: Mon, 21 Dec 2020 11:11:53 +0100
Subject: Pickling issue.
Message-ID: <07115ace-b3a0-d5bd-2c31-7f613ee98958@telenet.be>

Hi,

I've an object that I want to serialise with pickle.
When I reload the object the attributes of this object are correctly 
fixed except one of these.

This attribute (value) define a simple string.

Example:
---------------------------------------------
tag =? XmpTag('Xmp.dc.format', 'image/jpeg')
tag.key
'Xmp.dc.format'
tag.type
'MIMEType'
tag.value
'image/jpeg'

s = pickle.dumps(tag)
t = pickle.loads(s)
t.key
'Xmp.dc.format'???? # Correct
t.type
'MIMEType'????????? # Correct
t.value
('image', 'jpeg')?? # Not correct
---------------------------------------------

Tested with Python-3.8

An idea ?

From avigross at verizon.net  Mon Dec 21 16:22:02 2020
From: avigross at verizon.net (Avi Gross)
Date: Mon, 21 Dec 2020 16:22:02 -0500
Subject: How do you find what exceptions a class can throw?
In-Reply-To: <q456bh-mi1p.ln1@esprimo.zbmc.eu>
References: <20201220221532.GA14120@cskk.homeip.net>
 <trinity-5151abb1-8e85-4f3a-a89d-161901971f42-1608492843085@3c-app-gmx-bap51>
 <mailman.488.1608502543.7193.python-list@python.org>
 <12ee97ce-2c08-4e71-a554-57e5465517cfn@googlegroups.com>
 <0ad701d6d743$87c42e10$974c8a30$@verizon.net>
 <mailman.492.1608518814.7193.python-list@python.org>
 <q456bh-mi1p.ln1@esprimo.zbmc.eu>
Message-ID: <066801d6d7df$54beaf30$fe3c0d90$@verizon.net>

I agree Chris, that your original question is quite to the point. But is it always?

If you do something that tries to read a file (such as opening a database to send queries) on a remote server, how many different things might time out for various reasons? Some may resolve if you keep trying and some attempts may make it worse if everybody is pounding away resulting in a denial of service attack scenario.

Some people dealing with situations come up with more detailed attempts such as choosing a random interval before trying again. Protocols like the Post Office Protocol often already have built-in techniques like that in the protocol and the timeout may be caused by something in your chain not being set to wait long enough. 

So your attempt to retry a few times may well work. I wonder if a backup method would be to switch to using IMAP as many mail archives now support a way to approach them using several such interfaces, albeit perhaps to different destinations and other changes. But hat is not a trivial change to use as just an alternate. Trying again may work, albeit trying 100 times per second may not help if a server is rebooting or is out of memory or file space or other resources ...

I will say that if your function calls A() which calls B() and so on and the timeout happens at any place long the way or even at Z() then it is quite possible you may not get a specific exception back. Z() may indeed send back a TIMEOUT1 exception but then E() may intercept it and return a GENERIC_FAILURE12 exception. Then B() may retry a few times and finally return a I_GIVE_UP_TRY LATER123 exception. You likely are depending on a module you have no control over that uses other modules.

But in your case, it may indeed be that simple.

Just a thought. You can write some code that catches every possible exception then carefully logs all details, and then perhaps quits. If you run your code many times and even cause reasons for it to fail, you may develop some knowledge of some of the exceptions that make it through back to your call and then you can change your code to specifically handle only those you have some idea what to do about. As mentioned, you have traceback info that may help you figure out where the exceptions come from or even why.

Good luck.

-----Original Message-----
From: Python-list <python-list-bounces+avigross=verizon.net at python.org> On Behalf Of Chris Green
Sent: Monday, December 21, 2020 4:06 AM
To: python-list at python.org
Subject: Re: How do you find what exceptions a class can throw?

Avi Gross <avigross at verizon.net> wrote:
> The original question sounded like someone was asking what errors 
> might be thrown for a routine they wrote that used other components 
> that might directly throw exceptions or called yet others, ad nauseum.
> 
OP here.  The original question was because I wanted to trap timout errors when connectiing to a POP3 server in a very simple little program that collects mail and runs it through a filter before delivering it.

Thus I simply needed to know what the 'name' of the exception was so I could trap only timeouts.  Timeout errors are (probably) 'soft' errors which merit a retry, most other errors when trying to connect to a POP server would be unrecoverable (POP syntax, wrong name, wrong password, etc.).

It didn't seem such a difficult question when I asked it! :-)

--
Chris Green
?
--
https://mail.python.org/mailman/listinfo/python-list


From bgailer at gmail.com  Mon Dec 21 19:57:51 2020
From: bgailer at gmail.com (Bob Gailer)
Date: Mon, 21 Dec 2020 19:57:51 -0500
Subject: Pickling issue.
In-Reply-To: <07115ace-b3a0-d5bd-2c31-7f613ee98958@telenet.be>
References: <07115ace-b3a0-d5bd-2c31-7f613ee98958@telenet.be>
Message-ID: <CAP1rxO4dLG_ryYM4MqSgdG1m29Da64rpW9bKqLyrT-UOsosFUg@mail.gmail.com>

On Mon, Dec 21, 2020, 3:03 PM Vincent Vande Vyvre <
vincent.vande.vyvre at telenet.be> wrote:

> Hi,
>
> I've an object that I want to serialise with pickle.
> When I reload the object the attributes of this object are correctly
> fixed except one of these.
>
> This attribute (value) define a simple string.
>
> Example:
> ---------------------------------------------
> tag =  XmpTag('Xmp.dc.form'image/jpeg')


I am not familiar with XmpTag. Where might I get the containing module?

tag.key
> 'Xmp.dc.format'
> tag.type
> 'MIMEType'
> tag.value
> 'image/jpeg'
>
> s = pickle.dumps(tag)
> t = pickle.loads(s)
> t.key
> 'Xmp.dc.format'     # Correct
> t.type
> 'MIMEType'          # Correct
> t.value
> ('image', 'jpeg')   # Not correct
> ---------------------------------------------
>
> Tested with Python-3.8
>
> An idea ?
> --
> https://mail.python.org/mailman/listinfo/python-list
>

From walkmore99 at gmail.com  Tue Dec 22 06:16:52 2020
From: walkmore99 at gmail.com (Walk More)
Date: Tue, 22 Dec 2020 03:16:52 -0800 (PST)
Subject: Use dot notation to call a function without using parentheses
Message-ID: <b30061a8-d3ff-441e-bd8b-9eb84f69faeen@googlegroups.com>

I am trying to use dot notation to call a function without using parentheses, see code section with ***
I have looked into SimpleNamespace, namedTuple, dataclass... but no luck.
Below is my sample code to date.
Any suggestions?



class MyTest:
    def __init__(self):
        self.page1 = Page()
        self.page1.top = Counts()
        #self.page1.middle = Layout()
        #self.page1.bottom = Layout()
        
        # access of variables created on the fly using dot notation work.
        self.page1.top.item1 = 5
        self.page1.top.name1 = "Harry"
        print ("Variables created on the fly: ", self.page1.top.item1, self.page1.top.name1)
        
        
        # access of a predefined class variable using dot notation work.
        print ("Start of predefined class variable access: ", self.page1.top.totalCount)
        self.page1.top.totalCount = 22
        self.page1.top.totalCount = self.page1.top.totalCount + 3
        print ("End of predefined class variable access: ", self.page1.top.totalCount)
        
        
        # function calls using parentheses using dot notation work.
        print ("Start of function calls: ", self.page1.top.getRunningSum())
        self.page1.top.addRunningSum(5)
        self.page1.top.addRunningSum(200)
        endValue = self.page1.top.getRunningSum()
        print ("End of function calls: ", endValue)     


        # *** This is the syntax I would like to use. ***
        # function calls not using parentheses DO NOT WORK using dot notation.
        self.page1.top.addRunningSum = 6
        t = self.page1.top.getRunningSum
        print (t)
    
    
class Page ():
    def __init__ (self):
        pass
    
    
class Counts():
    def __init__ (self):    
        self.totalCount = 0    
    
    def addRunningSum(self, indata):
        self.totalCount = self.totalCount + indata
    
    def getRunningSum (self):
        return self.totalCount
    

if __name__ == "__main__":
    MyTest()

#end of program

From walkmore99 at gmail.com  Tue Dec 22 07:15:53 2020
From: walkmore99 at gmail.com (Walk More)
Date: Tue, 22 Dec 2020 04:15:53 -0800 (PST)
Subject: Use dot notation to call a function without using parentheses
In-Reply-To: <5fe1d8e3$0$8940$426a74cc@news.free.fr>
References: <b30061a8-d3ff-441e-bd8b-9eb84f69faeen@googlegroups.com>
 <5fe1d8e3$0$8940$426a74cc@news.free.fr>
Message-ID: <e63dfa49-5909-4d8e-b3ae-2f73e21a1df8n@googlegroups.com>

On Tuesday, December 22, 2020 at 6:31:08 AM UTC-5, Python wrote:
> Walk More wrote: 
> > I am trying to use dot notation to call a function without using parentheses, see code section with *** 
> > I have looked into SimpleNamespace, namedTuple, dataclass... but no luck. 
> > Below is my sample code to date. 
> > Any suggestions?
> accessors. 
> 
> class myClass: 
> @property 
> def data(self): 
> print('read data attribute') 
> return self._data 
> @data.setter 
> def data(self, value): 
> print('write data attribute') 
> self._data = value 
> def __init__(self, data=None): 
> self.data = data 
> 
> o = myClass('spam') 
> 
> print(o.data) 
> 
> o.data = 'ham' 
> 
> output: 
> 
> write data attribute 
> read data attribute 
> spam 
> write data attribute


Python,
Thank you very much for your solution.




From python at mrabarnett.plus.com  Tue Dec 22 07:20:01 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 22 Dec 2020 12:20:01 +0000
Subject: Use dot notation to call a function without using parentheses
In-Reply-To: <b30061a8-d3ff-441e-bd8b-9eb84f69faeen@googlegroups.com>
References: <b30061a8-d3ff-441e-bd8b-9eb84f69faeen@googlegroups.com>
Message-ID: <0d7271ff-06d0-7940-7893-351379ef7fe4@mrabarnett.plus.com>

On 2020-12-22 11:16, Walk More wrote:
> I am trying to use dot notation to call a function without using parentheses, see code section with ***
> I have looked into SimpleNamespace, namedTuple, dataclass... but no luck.
> Below is my sample code to date.
> Any suggestions?
> 
> 
> 
> class MyTest:
>      def __init__(self):
>          self.page1 = Page()
>          self.page1.top = Counts()
>          #self.page1.middle = Layout()
>          #self.page1.bottom = Layout()
>          
>          # access of variables created on the fly using dot notation work.
>          self.page1.top.item1 = 5
>          self.page1.top.name1 = "Harry"
>          print ("Variables created on the fly: ", self.page1.top.item1, self.page1.top.name1)
>          
>          
>          # access of a predefined class variable using dot notation work.
>          print ("Start of predefined class variable access: ", self.page1.top.totalCount)
>          self.page1.top.totalCount = 22
>          self.page1.top.totalCount = self.page1.top.totalCount + 3
>          print ("End of predefined class variable access: ", self.page1.top.totalCount)
>          
>          
>          # function calls using parentheses using dot notation work.
>          print ("Start of function calls: ", self.page1.top.getRunningSum())
>          self.page1.top.addRunningSum(5)
>          self.page1.top.addRunningSum(200)
>          endValue = self.page1.top.getRunningSum()
>          print ("End of function calls: ", endValue)
> 
> 
>          # *** This is the syntax I would like to use. ***
>          # function calls not using parentheses DO NOT WORK using dot notation.
>          self.page1.top.addRunningSum = 6
>          t = self.page1.top.getRunningSum
>          print (t)
>      
>      
> class Page ():
>      def __init__ (self):
>          pass
>      
>      
> class Counts():
>      def __init__ (self):
>          self.totalCount = 0
>      
>      def addRunningSum(self, indata):
>          self.totalCount = self.totalCount + indata
>      
>      def getRunningSum (self):
>          return self.totalCount
>      
> 
> if __name__ == "__main__":
>      MyTest()
> 
> #end of program
> 
It would be simpler just to access the totalCount attribute directly, 
but, in answer to your question, you can make it a property:

      @property
      def getRunningSum(self):
          return self.totalCount

and you'll then need to remove the parenthese where you're calling it.

From cl at isbd.net  Tue Dec 22 10:10:56 2020
From: cl at isbd.net (Chris Green)
Date: Tue, 22 Dec 2020 15:10:56 +0000
Subject: Installing Python (2.7) 'by hand' on Ubuntu - possible?
Message-ID: <0te9bh-52nv.ln1@esprimo.zbmc.eu>

I have (as discussed here) a printer utility that uses Python 2 and I
can't update it to Python 3 because it has a .so library file which is
compiled for Python 2.  I think I have exhausted all the possibilities
for converting it to Python 3 so now I'm looking at how to keep it
working on my [x]ubuntu Linux systems as Python 2.7 becomes unsupported.

How realistic/possible would it be to run the utility in a separate
environment with its own copies of Python2 and any modules and
libraries needed?  I would install these 'by hand', i.e. not using
'apt' so they would stay as installed even as my system gets upgraded. 

There would obviously be *some* dependencies on the system libraries
but I think they'd be pretty low level and thus their interfaces would
be very unlikely to change for a long time so I should be able to run
my old Python2.7 and the Python modules needed for the utility for
quite a few years anyway (the printer it supports will wear out
eventually!).

-- 
Chris Green
?

From torriem at gmail.com  Tue Dec 22 11:19:55 2020
From: torriem at gmail.com (Michael Torrie)
Date: Tue, 22 Dec 2020 09:19:55 -0700
Subject: Installing Python (2.7) 'by hand' on Ubuntu - possible?
In-Reply-To: <0te9bh-52nv.ln1@esprimo.zbmc.eu>
References: <0te9bh-52nv.ln1@esprimo.zbmc.eu>
Message-ID: <302033ef-5b6e-dd67-5323-19437fd84b37@gmail.com>

On 12/22/20 8:10 AM, Chris Green wrote:
> I have (as discussed here) a printer utility that uses Python 2 and I
> can't update it to Python 3 because it has a .so library file which is
> compiled for Python 2.  I think I have exhausted all the possibilities
> for converting it to Python 3 so now I'm looking at how to keep it
> working on my [x]ubuntu Linux systems as Python 2.7 becomes unsupported.
> 
> How realistic/possible would it be to run the utility in a separate
> environment with its own copies of Python2 and any modules and
> libraries needed?  I would install these 'by hand', i.e. not using
> 'apt' so they would stay as installed even as my system gets upgraded. 
> 
> There would obviously be *some* dependencies on the system libraries
> but I think they'd be pretty low level and thus their interfaces would
> be very unlikely to change for a long time so I should be able to run
> my old Python2.7 and the Python modules needed for the utility for
> quite a few years anyway (the printer it supports will wear out
> eventually!).

Probably your best bet is to build a container image (perhaps a snap)
around with a distro that has Python 2.7 in it to house your app. That
way you've got everything you need including the required system
libraries.  Right now you could build a image of it based on Ubuntu
20.04 which has python 2.7 as an optional installable package.

Sure you could build Python 2.7 for as long as the compatible compilers
and other dependent libraries are available.  I expect RHEL to keep
building python 2.7 for another 10 years.  Ubuntu 20.04 will continue to
ship python 2.7 as an optional package for another 5 years at least.

There are ways even besides containers that work. With some scripts to
set up custom library paths and trees of custom libraries, you can run
old binary software on newer distros even. With some help from the
interwebs, I am able to run WordPerfect 8 for Linux on my Fedora 32 box.
 That was released back in the kernel 2.0 days, before the transition to
glibc.

From grant.b.edwards at gmail.com  Tue Dec 22 10:48:43 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Tue, 22 Dec 2020 15:48:43 -0000 (UTC)
Subject: Installing Python (2.7) 'by hand' on Ubuntu - possible?
References: <0te9bh-52nv.ln1@esprimo.zbmc.eu>
Message-ID: <rrt4gr$bjp$1@ciao.gmane.io>

On 2020-12-22, Chris Green <cl at isbd.net> wrote:
> I have (as discussed here) a printer utility that uses Python 2 and I
> can't update it to Python 3 because it has a .so library file which is
> compiled for Python 2.  I think I have exhausted all the possibilities
> for converting it to Python 3 so now I'm looking at how to keep it
> working on my [x]ubuntu Linux systems as Python 2.7 becomes unsupported.
>
> How realistic/possible would it be to run the utility in a separate
> environment with its own copies of Python2 and any modules and
> libraries needed?

That depends on the modules and libraries needed. If it's just
python2, it should be pretty easy. If it needs things like GTK or Qt,
it gets a _lot_ harder.

-- 
Grant


From cl at isbd.net  Tue Dec 22 11:44:42 2020
From: cl at isbd.net (Chris Green)
Date: Tue, 22 Dec 2020 16:44:42 +0000
Subject: Installing Python (2.7) 'by hand' on Ubuntu - possible?
References: <0te9bh-52nv.ln1@esprimo.zbmc.eu>
 <302033ef-5b6e-dd67-5323-19437fd84b37@gmail.com>
 <mailman.506.1608654000.7193.python-list@python.org>
Message-ID: <qck9bh-3c301.ln1@esprimo.zbmc.eu>

Michael Torrie <torriem at gmail.com> wrote:
> On 12/22/20 8:10 AM, Chris Green wrote:
> > I have (as discussed here) a printer utility that uses Python 2 and I
> > can't update it to Python 3 because it has a .so library file which is
> > compiled for Python 2.  I think I have exhausted all the possibilities
> > for converting it to Python 3 so now I'm looking at how to keep it
> > working on my [x]ubuntu Linux systems as Python 2.7 becomes unsupported.
> > 
> > How realistic/possible would it be to run the utility in a separate
> > environment with its own copies of Python2 and any modules and
> > libraries needed?  I would install these 'by hand', i.e. not using
> > 'apt' so they would stay as installed even as my system gets upgraded. 
> > 
> > There would obviously be *some* dependencies on the system libraries
> > but I think they'd be pretty low level and thus their interfaces would
> > be very unlikely to change for a long time so I should be able to run
> > my old Python2.7 and the Python modules needed for the utility for
> > quite a few years anyway (the printer it supports will wear out
> > eventually!).
> 
> Probably your best bet is to build a container image (perhaps a snap)
> around with a distro that has Python 2.7 in it to house your app. That
> way you've got everything you need including the required system
> libraries.  Right now you could build a image of it based on Ubuntu
> 20.04 which has python 2.7 as an optional installable package.
> 
I have it running on 20.04 (with a couple of compatibility packages
from a PPA) but I know I start hitting problems as soon as I move to
20.10.  So that does sound like an excellent idea.  Where can I find
information about building container type things like snap?

-- 
Chris Green
?

From torriem at gmail.com  Tue Dec 22 12:10:21 2020
From: torriem at gmail.com (Michael Torrie)
Date: Tue, 22 Dec 2020 10:10:21 -0700
Subject: Installing Python (2.7) 'by hand' on Ubuntu - possible?
In-Reply-To: <qck9bh-3c301.ln1@esprimo.zbmc.eu>
References: <0te9bh-52nv.ln1@esprimo.zbmc.eu>
 <302033ef-5b6e-dd67-5323-19437fd84b37@gmail.com>
 <mailman.506.1608654000.7193.python-list@python.org>
 <qck9bh-3c301.ln1@esprimo.zbmc.eu>
Message-ID: <3a57b1de-c402-4376-ffee-d4b82dbf88e4@gmail.com>

On 12/22/20 9:44 AM, Chris Green wrote:
> I have it running on 20.04 (with a couple of compatibility packages
> from a PPA) but I know I start hitting problems as soon as I move to
> 20.10.  So that does sound like an excellent idea.  Where can I find
> information about building container type things like snap?

Good question.  A quick search reveals this potential starting place:
https://ubuntu.com/tutorials/create-your-first-snap

Also
https://snapcraft.io/docs/python-plugin
https://snapcraft.io/docs/python-apps

That's all I know. Sorry I suggested a solution I know nothing about!



From grant.b.edwards at gmail.com  Tue Dec 22 12:18:31 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Tue, 22 Dec 2020 17:18:31 -0000 (UTC)
Subject: Installing Python (2.7) 'by hand' on Ubuntu - possible?
References: <0te9bh-52nv.ln1@esprimo.zbmc.eu>
Message-ID: <rrt9p7$139p$1@ciao.gmane.io>

On 2020-12-22, Chris Green <cl at isbd.net> wrote:
> [...]
>
> How realistic/possible would it be to run the utility in a separate
> environment with its own copies of Python2 and any modules and
> libraries needed?  I would install these 'by hand', i.e. not using
> 'apt' so they would stay as installed even as my system gets upgraded.

If you do have it running on a Linux system, then there are tools to
"bundle" it with all the required libraries. The one that I've used
most recently is cx_freeze (I generally use it to create bundles for
Windows):

https://cx-freeze.readthedocs.io/en/latest/index.html

If you want to use it for a 2.7 app, you'd need to use 5.1

--
Grant



From rosuav at gmail.com  Tue Dec 22 13:32:50 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 23 Dec 2020 05:32:50 +1100
Subject: Installing Python (2.7) 'by hand' on Ubuntu - possible?
In-Reply-To: <0te9bh-52nv.ln1@esprimo.zbmc.eu>
References: <0te9bh-52nv.ln1@esprimo.zbmc.eu>
Message-ID: <CAPTjJmrsw8eeC2XrJSTgdOfZqw=wkgYCKs1+kjx+BejKMtyqaQ@mail.gmail.com>

On Wed, Dec 23, 2020 at 2:21 AM Chris Green <cl at isbd.net> wrote:
>
> I have (as discussed here) a printer utility that uses Python 2 and I
> can't update it to Python 3 because it has a .so library file which is
> compiled for Python 2.  I think I have exhausted all the possibilities
> for converting it to Python 3 so now I'm looking at how to keep it
> working on my [x]ubuntu Linux systems as Python 2.7 becomes unsupported.
>
> How realistic/possible would it be to run the utility in a separate
> environment with its own copies of Python2 and any modules and
> libraries needed?  I would install these 'by hand', i.e. not using
> 'apt' so they would stay as installed even as my system gets upgraded.
>

It shouldn't be too hard to grab the source code for Python 2.7 and
install it that way. The first step would be to ask apt to install all
the build dependencies of Python 3; the same libraries will be
important for building Python 2 (bar a couple that got added more
recently, but that won't affect anything).

Once you get it built, you can either just install it as is, or build
yourself a package (with checkinstall or something) to be able to
uninstall later. Personally, I'd just install it directly, but that's
me.

ChrisA

From cl at isbd.net  Tue Dec 22 13:38:04 2020
From: cl at isbd.net (Chris Green)
Date: Tue, 22 Dec 2020 18:38:04 +0000
Subject: Installing Python (2.7) 'by hand' on Ubuntu - possible?
References: <0te9bh-52nv.ln1@esprimo.zbmc.eu> <rrt9p7$139p$1@ciao.gmane.io>
 <mailman.509.1608657686.7193.python-list@python.org>
Message-ID: <c1r9bh-img01.ln1@esprimo.zbmc.eu>

Grant Edwards <grant.b.edwards at gmail.com> wrote:
> On 2020-12-22, Chris Green <cl at isbd.net> wrote:
> > [...]
> >
> > How realistic/possible would it be to run the utility in a separate
> > environment with its own copies of Python2 and any modules and
> > libraries needed?  I would install these 'by hand', i.e. not using
> > 'apt' so they would stay as installed even as my system gets upgraded.
> 
> If you do have it running on a Linux system, then there are tools to
> "bundle" it with all the required libraries. The one that I've used
> most recently is cx_freeze (I generally use it to create bundles for
> Windows):
> 
> https://cx-freeze.readthedocs.io/en/latest/index.html
> 
> If you want to use it for a 2.7 app, you'd need to use 5.1
> 
That looks a good approach, thank you.

-- 
Chris Green
?

From grant.b.edwards at gmail.com  Tue Dec 22 13:58:52 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Tue, 22 Dec 2020 18:58:52 -0000 (UTC)
Subject: Installing Python (2.7) 'by hand' on Ubuntu - possible?
References: <0te9bh-52nv.ln1@esprimo.zbmc.eu> <rrt9p7$139p$1@ciao.gmane.io>
 <mailman.509.1608657686.7193.python-list@python.org>
 <c1r9bh-img01.ln1@esprimo.zbmc.eu>
Message-ID: <rrtflc$2md$1@ciao.gmane.io>

On 2020-12-22, Chris Green <cl at isbd.net> wrote:
> Grant Edwards <grant.b.edwards at gmail.com> wrote:
>> On 2020-12-22, Chris Green <cl at isbd.net> wrote:
>> > [...]
>> >
>> > How realistic/possible would it be to run the utility in a separate
>> > environment with its own copies of Python2 and any modules and
>> > libraries needed?  I would install these 'by hand', i.e. not using
>> > 'apt' so they would stay as installed even as my system gets upgraded.
>> 
>> If you do have it running on a Linux system, then there are tools to
>> "bundle" it with all the required libraries. The one that I've used
>> most recently is cx_freeze (I generally use it to create bundles for
>> Windows):
>> 
>> https://cx-freeze.readthedocs.io/en/latest/index.html
>> 
>> If you want to use it for a 2.7 app, you'd need to use 5.1
>
> That looks a good approach, thank you.

I should have mentioned that bundlers like cx_freeze require that you
have the Python source for the main app. I don't remember if you
mentioned source or not...

--
Grant




From cl at isbd.net  Tue Dec 22 14:24:19 2020
From: cl at isbd.net (Chris Green)
Date: Tue, 22 Dec 2020 19:24:19 +0000
Subject: Installing Python (2.7) 'by hand' on Ubuntu - possible?
References: <0te9bh-52nv.ln1@esprimo.zbmc.eu> <rrt9p7$139p$1@ciao.gmane.io>
 <mailman.509.1608657686.7193.python-list@python.org>
 <c1r9bh-img01.ln1@esprimo.zbmc.eu> <rrtflc$2md$1@ciao.gmane.io>
 <mailman.511.1608663894.7193.python-list@python.org>
Message-ID: <3ot9bh-o5m01.ln1@esprimo.zbmc.eu>

Grant Edwards <grant.b.edwards at gmail.com> wrote:
> On 2020-12-22, Chris Green <cl at isbd.net> wrote:
> > Grant Edwards <grant.b.edwards at gmail.com> wrote:
> >> On 2020-12-22, Chris Green <cl at isbd.net> wrote:
> >> > [...]
> >> >
> >> > How realistic/possible would it be to run the utility in a separate
> >> > environment with its own copies of Python2 and any modules and
> >> > libraries needed?  I would install these 'by hand', i.e. not using
> >> > 'apt' so they would stay as installed even as my system gets upgraded.
> >> 
> >> If you do have it running on a Linux system, then there are tools to
> >> "bundle" it with all the required libraries. The one that I've used
> >> most recently is cx_freeze (I generally use it to create bundles for
> >> Windows):
> >> 
> >> https://cx-freeze.readthedocs.io/en/latest/index.html
> >> 
> >> If you want to use it for a 2.7 app, you'd need to use 5.1
> >
> > That looks a good approach, thank you.
> 
> I should have mentioned that bundlers like cx_freeze require that you
> have the Python source for the main app. I don't remember if you
> mentioned source or not...
> 
Yes, I do have the Python source.  The only thing I don't have the
source for is a .so file and that's why I can't simply migrate the
program(s) from Python 2 to Python 3.

-- 
Chris Green
?

From grant.b.edwards at gmail.com  Tue Dec 22 14:41:44 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Tue, 22 Dec 2020 19:41:44 -0000 (UTC)
Subject: Installing Python (2.7) 'by hand' on Ubuntu - possible?
References: <0te9bh-52nv.ln1@esprimo.zbmc.eu> <rrt9p7$139p$1@ciao.gmane.io>
 <mailman.509.1608657686.7193.python-list@python.org>
 <c1r9bh-img01.ln1@esprimo.zbmc.eu> <rrtflc$2md$1@ciao.gmane.io>
 <mailman.511.1608663894.7193.python-list@python.org>
 <3ot9bh-o5m01.ln1@esprimo.zbmc.eu>
Message-ID: <rrti5o$106t$1@ciao.gmane.io>

On 2020-12-22, Chris Green <cl at isbd.net> wrote:
> Grant Edwards <grant.b.edwards at gmail.com> wrote:
>
>> I should have mentioned that bundlers like cx_freeze require that you
>> have the Python source for the main app. I don't remember if you
>> mentioned source or not...
>
> Yes, I do have the Python source.  The only thing I don't have the
> source for is a .so file and that's why I can't simply migrate the
> program(s) from Python 2 to Python 3.

I think cx_freeze should be able to do the job. It tries to
auto-detect what libraries and Python modules are needed, but
sometimes you have manually add one or two to the list.

--
Grant


From mirkok.lists at googlemail.com  Tue Dec 22 16:12:34 2020
From: mirkok.lists at googlemail.com (Mirko)
Date: Tue, 22 Dec 2020 22:12:34 +0100
Subject: Installing Python (2.7) 'by hand' on Ubuntu - possible?
In-Reply-To: <3ot9bh-o5m01.ln1@esprimo.zbmc.eu>
References: <0te9bh-52nv.ln1@esprimo.zbmc.eu> <rrt9p7$139p$1@ciao.gmane.io>
 <mailman.509.1608657686.7193.python-list@python.org>
 <c1r9bh-img01.ln1@esprimo.zbmc.eu> <rrtflc$2md$1@ciao.gmane.io>
 <mailman.511.1608663894.7193.python-list@python.org>
 <3ot9bh-o5m01.ln1@esprimo.zbmc.eu>
Message-ID: <5FE26142.5090209@googlemail.com>

On 22.12.2020 at 20:24 Chris Green wrote:

> Yes, I do have the Python source.  The only thing I don't have the
> source for is a .so file and that's why I can't simply migrate the
> program(s) from Python 2 to Python 3.
> 

If it's just one .so and that library is compatible with basic libs
such as glibc and has no further big dependencies, then there may be
a simpler way than cx_freeze or even snap/docker/etc.

Python 2 will likely be available for quite some more years as an
optional package. But even with a self-compiled version, you should
be able to put the required libraries somewhere and set
LD_LIBRARY_PATH or maybe LD_PRELOAD accordingly. For a few depending
libs, this works well, but it gets really nasty if glibc or big
frameworks such as GTK are involved.

From rhettprince at gmail.com  Tue Dec 22 18:57:14 2020
From: rhettprince at gmail.com (Rhett Prince)
Date: Tue, 22 Dec 2020 18:57:14 -0500
Subject: sqlalchemy blows up and puts in addresses instead of data when mixing
 fields from different dataframes
Message-ID: <000701d6d8be$2c567de0$850379a0$@gmail.com>

sqlalchemy blows up  and puts in addresses instead of data when mixing
fields from different dataframes

 

when composing a class derived from model, 

populating fields from different dataframes blows up.fields from one data
frame are corrupted after 

session add and session commit 

fields from another dataframe are fine. 

 

building final class object with single dataframe from data frame with the
issue alone is just fine. 

data from the data frame survives session.add and session.commit 

 

data is only corrupted when data comes from two different data frame sources


field 1 comes from data frame a 

field 2 comes from dataframe b

after session.add session.commit 

first field from source 1 is corrupted. 

data from source 2 is fine. 

 

again 

when data source 1 is used by itself with out a second source 

data from dataframe 1 survives 

session.add and session.commit. 

 

is this a defect in sqlalchemy or in pandas. 

o


From jcasale at activenetwerx.com  Tue Dec 22 23:04:24 2020
From: jcasale at activenetwerx.com (Joseph L. Casale)
Date: Wed, 23 Dec 2020 04:04:24 +0000
Subject: pexpect with kadmin
Message-ID: <57b0a153b1884f3a8f12215183c6ab9e@activenetwerx.com>

Anyone ever used pexpect with tooling like kadmin and have
insight into how to manage interacting with it?

After setting up debug logging, I was able to adjust the expect
usage to get the input and output logs to at least appear correct
when setting a password for a principal, however even with a
successful return code from kadmin, there is some discrepancy
and the credential is not being set right.

When run manually, the credentials work fine, it's almost as if
kadmin is swallowing the newline from pexpect within the password.

I am using python 3.5 from Windows, over plink.exe, onto a rhel
7 server. Unfortunately, I am stuck with all the levels of indirection.

Thanks,
jlc

From cl at isbd.net  Wed Dec 23 04:03:27 2020
From: cl at isbd.net (Chris Green)
Date: Wed, 23 Dec 2020 09:03:27 +0000
Subject: Installing Python (2.7) 'by hand' on Ubuntu - possible?
References: <0te9bh-52nv.ln1@esprimo.zbmc.eu> <rrt9p7$139p$1@ciao.gmane.io>
 <mailman.509.1608657686.7193.python-list@python.org>
 <c1r9bh-img01.ln1@esprimo.zbmc.eu> <rrtflc$2md$1@ciao.gmane.io>
 <mailman.511.1608663894.7193.python-list@python.org>
 <3ot9bh-o5m01.ln1@esprimo.zbmc.eu> <5FE26142.5090209@googlemail.com>
 <mailman.513.1608671557.7193.python-list@python.org>
Message-ID: <vndbbh-iun31.ln1@esprimo.zbmc.eu>

Mirko <mirkok.lists at googlemail.com> wrote:
> On 22.12.2020 at 20:24 Chris Green wrote:
> 
> > Yes, I do have the Python source.  The only thing I don't have the
> > source for is a .so file and that's why I can't simply migrate the
> > program(s) from Python 2 to Python 3.
> > 
> 
> If it's just one .so and that library is compatible with basic libs
> such as glibc and has no further big dependencies, then there may be
> a simpler way than cx_freeze or even snap/docker/etc.
> 
> Python 2 will likely be available for quite some more years as an
> optional package. But even with a self-compiled version, you should
> be able to put the required libraries somewhere and set
> LD_LIBRARY_PATH or maybe LD_PRELOAD accordingly. For a few depending
> libs, this works well, but it gets really nasty if glibc or big
> frameworks such as GTK are involved.

Unfortunately GTK is involved, the utility pops up a GUI that uses
Gtk2, that's part of the can of worms that this has become because of
the non-trivial migration of GTK from Python 2 to Python 3.

As I said I have the Python source and it's not particularly difficult
to move that from Python 2 to Python 3, the killer is a .so compiled
for Python 2.

-- 
Chris Green
?

From barry at barrys-emacs.org  Wed Dec 23 10:00:19 2020
From: barry at barrys-emacs.org (Barry Scott)
Date: Wed, 23 Dec 2020 15:00:19 +0000
Subject: pexpect with kadmin
In-Reply-To: <57b0a153b1884f3a8f12215183c6ab9e@activenetwerx.com>
References: <57b0a153b1884f3a8f12215183c6ab9e@activenetwerx.com>
Message-ID: <7F3D51C0-60A3-44BE-AB00-54C788117F95@barrys-emacs.org>



> On 23 Dec 2020, at 04:04, Joseph L. Casale <jcasale at activenetwerx.com> wrote:
> 
> Anyone ever used pexpect with tooling like kadmin and have
> insight into how to manage interacting with it?
> 
> After setting up debug logging, I was able to adjust the expect
> usage to get the input and output logs to at least appear correct
> when setting a password for a principal, however even with a
> successful return code from kadmin, there is some discrepancy
> and the credential is not being set right.
> 
> When run manually, the credentials work fine, it's almost as if
> kadmin is swallowing the newline from pexpect within the password.
> 
> I am using python 3.5 from Windows, over plink.exe, onto a rhel
> 7 server. Unfortunately, I am stuck with all the levels of indirection.

If you have windows 10 can you use Windows Subsystem for Linux  (WSL)
to install one of the Linux distros and use that?

Barry

> 
> Thanks,
> jlc
> -- 
> https://mail.python.org/mailman/listinfo/python-list
> 


From vincent.vandevyvre at oqapy.eu  Wed Dec 23 03:31:00 2020
From: vincent.vandevyvre at oqapy.eu (vincent.vandevyvre at oqapy.eu)
Date: Wed, 23 Dec 2020 03:31:00 -0500 (EST)
Subject: Pickling issue.
Message-ID: <20201223092247.7kNn2400E5Fqe7q01kNnAN@xavier.telenet-ops.be>

On 22/12/20 01:57, Bob Gailer wrote:
>
>
> On Mon, Dec 21, 2020, 3:03 PM Vincent Vande Vyvre <vincent.vande.vyvre at telenet.be> wrote:
>
>     Hi,
>
>     I've an object that I want to serialise with pickle.
>     When I reload the object the attributes of this object are correctly
>     fixed except one of these.
>
>     This attribute (value) define a simple string.
>
>     Example:
>     ---------------------------------------------
>     tag =  XmpTag('Xmp.dc.form'image/jpeg')
>
>
> I am not familiar with XmpTag. Where might I get the containing module?
>
>     ... skip
>
Yes, it's available with pip:
https://pypi.org/project/py3exiv2/
If you want to test it, just add from pyexiv2.xmp import XmpTag to my example.

and the source is here:
https://bazaar.launchpad.net/~vincent-vandevyvre/py3exiv2/trunk/view/head:/py3exiv2/src/pyexiv2/xmp.py

This is a Python-3 binding of the lib exiv2, the wrapper source code is here:
https://bazaar.launchpad.net/~vincent-vandevyvre/py3exiv2/trunk/view/head:/py3exiv2/src/exiv2wrapper.cpp#L359

exiv2 doc is here:
https://www.exiv2.org/doc/classExiv2_1_1Xmpdatum.html

Sorry for the late response but it seems a moderation problem with my account.

Vincent

From sersadaka1 at outlook.com  Wed Dec 23 12:03:51 2020
From: sersadaka1 at outlook.com (Sadaka Technology)
Date: Wed, 23 Dec 2020 09:03:51 -0800 (PST)
Subject: using regex for password validation
Message-ID: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>

hello guys,

I have this pattern for password validation (regex):

I want these rules to be applied:

Minimum 8 characters.
The alphabets must be between [a-z]
At least one alphabet should be of Upper Case [A-Z]
At least 1 number or digit between [0-9].
At least 1 character from [ _ or @ or $ ].

and this pattern:

passwordpattern = "^(?=.[a-z])(?=.[A-Z])(?=.\d)(?=.[@$])[A-Za-z\d@$!%?&]{8,}.$"

my only issue is that I want to add the symbol () and symbol(.) in the pattern where only it accepts $ and @, I tried adding generally like [@_$] not working

From mats at wichmann.us  Wed Dec 23 13:46:36 2020
From: mats at wichmann.us (Mats Wichmann)
Date: Wed, 23 Dec 2020 11:46:36 -0700
Subject: using regex for password validation
In-Reply-To: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
References: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
Message-ID: <c94a1ee0-557d-abce-570f-fad3347bc86c@wichmann.us>

On 12/23/20 10:03 AM, Sadaka Technology wrote:
> hello guys,
> 
> I have this pattern for password validation (regex):
> 
> I want these rules to be applied:
> 
> Minimum 8 characters.
> The alphabets must be between [a-z]
> At least one alphabet should be of Upper Case [A-Z]
> At least 1 number or digit between [0-9].
> At least 1 character from [ _ or @ or $ ].
> 
> and this pattern:
> 
> passwordpattern = "^(?=.[a-z])(?=.[A-Z])(?=.\d)(?=.[@$])[A-Za-z\d@$!%?&]{8,}.$"
> 
> my only issue is that I want to add the symbol () and symbol(.) in the pattern where only it accepts $ and @, I tried adding generally like [@_$] not working
> 

I'm not going to answer your question, don't have the brainpower at the 
moment to disentangle your regex.

Therein comes the source of the (unasked-for) comment: if looking at a 
regex gives you a headache - and worse, it doesn't work as you hope, you 
probably want to solve a problem another way.

If you're enforcing a password policy (and this isn't a homework 
question, where the rules conveniently don't change over time), I'd 
claim you're better off writing a readable routine that applies the 
policy in such a way that you can accommodate changes to the policy. 
What if someone decides that the non-alnum set can also include a comma 
or other characters? What if there's a different constraint applied to 
the first character of the password?  (both of those are moderately common).

Telling someone the password they tried to propose doesn't meet the 
policy isn't performance sensitive, since it is a human-interactive 
process, so it's okay to be a little slower and a lot clearer (that's 
not even a Python issue!)

If you're going to stick with a regex, run the completed regex through 
one of the online validators, and paste its analysis (they usually give 
you a breakdown of what each piece means) as a comment, so some future 
programmer has a hope...




From python at mrabarnett.plus.com  Wed Dec 23 14:03:50 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Wed, 23 Dec 2020 19:03:50 +0000
Subject: using regex for password validation
In-Reply-To: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
References: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
Message-ID: <cedd778a-b553-3f60-9b3c-21ba1c0be788@mrabarnett.plus.com>

On 2020-12-23 17:03, Sadaka Technology wrote:
> hello guys,
> 
> I have this pattern for password validation (regex):
> 
> I want these rules to be applied:
> 
> Minimum 8 characters.
> The alphabets must be between [a-z]
> At least one alphabet should be of Upper Case [A-Z]
> At least 1 number or digit between [0-9].
> At least 1 character from [ _ or @ or $ ].
> 
> and this pattern:
> 
> passwordpattern = "^(?=.[a-z])(?=.[A-Z])(?=.\d)(?=.[@$])[A-Za-z\d@$!%?&]{8,}.$"
> 
> my only issue is that I want to add the symbol () and symbol(.) in the pattern where only it accepts $ and @, I tried adding generally like [@_$] not working
> 
Your pattern:

^		        Matches at start of string
(?=.[a-z])	        Matches any character and then one [a-z]
(?=.[A-Z])	        Matches any character and then one [A-Z]
(?=.\d)		        Matches any character and then one digit
(?=.[@$])	        Matches any character and then one of [@$]
[A-Za-z\d@$!%?&]{8,}	Matches 8 or more of [A-Za-z\d@$!%?&]{8,}
.			Matches any character
$			Matche at end of string

The pattern will never match because the second character cannot be one 
of [a-z] _and_ one of [A-Z] _and_ a digit _and_ one of [@$] _at the same 
time_.

I'm not sure what you mean by "The alphabets must be between [a-z]" (all 
letters lower case?) and also "At least one alphabet should be of Upper 
Case [A-Z]" (at least one upper case letter).

I'm guessing you mean that all letters must be [A-Za-z], but at least 
one of them must be [A-Z].

Also, what do you mean by "symbol () and symbol(.)"; I see the "." 
between the second parentheses in the second one, but nothing between 
the first.

Anyway, how about this pattern:

^(?=.*[A-Z])(?=.*[0-9])(?=.*[_@$])[A-Za-z0-9@$_!%?&]{8,}$


From grant.b.edwards at gmail.com  Wed Dec 23 15:41:01 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Wed, 23 Dec 2020 20:41:01 -0000 (UTC)
Subject: using regex for password validation
References: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
 <c94a1ee0-557d-abce-570f-fad3347bc86c@wichmann.us>
Message-ID: <rs0a0t$gqf$1@ciao.gmane.io>

On 2020-12-23, Mats Wichmann <mats at wichmann.us> wrote:

> Telling someone the password they tried to propose doesn't meet the 
> policy isn't performance sensitive, since it is a human-interactive 
> process, so it's okay to be a little slower and a lot clearer (that's 
> not even a Python issue!)

You're far, far better off writing a function that tests each rule
separately, so that you can tell the user _why_ the password isn't
allowed. If you use a regex, it's just pass/fail. The user won't have
any idea how to fix the problem.

-- 
Grant Edwards               grant.b.edwards        Yow! With YOU, I can be
                                  at               MYSELF ...  We don't NEED
                              gmail.com            Dan Rather ...


From rosuav at gmail.com  Wed Dec 23 17:03:53 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 24 Dec 2020 09:03:53 +1100
Subject: using regex for password validation
In-Reply-To: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
References: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
Message-ID: <CAPTjJmrq3yBF4YehC607bBiE8kSyzJhP5d3Vj_FoA0sMYKg6xQ@mail.gmail.com>

On Thu, Dec 24, 2020 at 4:09 AM Sadaka Technology
<sersadaka1 at outlook.com> wrote:
>
> hello guys,
>
> I have this pattern for password validation (regex):
>
> I want these rules to be applied:
>
> Minimum 8 characters.
> The alphabets must be between [a-z]
> At least one alphabet should be of Upper Case [A-Z]
> At least 1 number or digit between [0-9].
> At least 1 character from [ _ or @ or $ ].
>
> and this pattern:
>
> passwordpattern = "^(?=.[a-z])(?=.[A-Z])(?=.\d)(?=.[@$])[A-Za-z\d@$!%?&]{8,}.$"
>
> my only issue is that I want to add the symbol () and symbol(.) in the pattern where only it accepts $ and @, I tried adding generally like [@_$] not working
>

Easy solution:

passwordpattern = ".{11,}"

This mandates more security than the one you're using, AND it's far
less frustrating for users.

Please stop inflicting horrific password rules on the world.
Especially, requiring one "symbol" - where "symbol" is always defined
differently from one place to another (and in your case, you're
offering just three valid options) - causes weaker passwords and more
frustration.

Just don't do it.

ChrisA

From jcasale at activenetwerx.com  Wed Dec 23 17:07:09 2020
From: jcasale at activenetwerx.com (Joseph L. Casale)
Date: Wed, 23 Dec 2020 22:07:09 +0000
Subject: pexpect with kadmin
In-Reply-To: <7F3D51C0-60A3-44BE-AB00-54C788117F95@barrys-emacs.org>
References: <57b0a153b1884f3a8f12215183c6ab9e@activenetwerx.com>
 <7F3D51C0-60A3-44BE-AB00-54C788117F95@barrys-emacs.org>
Message-ID: <61e0387bd9ab42a4ae90ec6d70b4e75d@activenetwerx.com>

> If you have windows 10 can you use Windows Subsystem for Linux  (WSL)
> to install one of the Linux distros and use that?

Interesting idea, sadly I am too far past the deadline on this to go through
the red tape needed to get that in place.

Thanks,
jlc


From PythonList at DancesWithMice.info  Wed Dec 23 17:41:15 2020
From: PythonList at DancesWithMice.info (dn)
Date: Thu, 24 Dec 2020 11:41:15 +1300
Subject: using regex for password validation
In-Reply-To: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
References: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
Message-ID: <36c7f24e-5410-26a2-6070-74336e71ffdb@DancesWithMice.info>

On 24/12/2020 06:03, Sadaka Technology wrote:
> hello guys,
> 
> I have this pattern for password validation (regex):
> 
> I want these rules to be applied:
> 
> Minimum 8 characters.
> The alphabets must be between [a-z]
> At least one alphabet should be of Upper Case [A-Z]
> At least 1 number or digit between [0-9].
> At least 1 character from [ _ or @ or $ ].
> 
> and this pattern:
> 
> passwordpattern = "^(?=.[a-z])(?=.[A-Z])(?=.\d)(?=.[@$])[A-Za-z\d@$!%?&]{8,}.$"
> 
> my only issue is that I want to add the symbol () and symbol(.) in the pattern where only it accepts $ and @, I tried adding generally like [@_$] not working


A quick web.search reveals, quite evidently, loads of people attempt to 
solve this problem with ever more-powerful RegExs. (and ever more 
perplexing questions on SO, etc)

There's something seductive about RegEx-s to the average ComSc student. 
The challenge of wielding such control, so concisely. APL or Lisp 
programming anyone? I recall positively-devouring Jeff Friedl's book - 
with expectations of 'changing the world'...

[back down to earth] These days I seldom use them (NB ActiveState do?did 
a (recommended) 'cheat sheet', a copy of which resides in my desk-file 
as crib-notes)


Contrarily, a RegEx may be quite the wrong tool for the job. Partially 
because such expressions are difficult to understand - either someone 
else's code or my own from the proverbial six-months back(!); and 
partially here we're attempting to solve multiple problems in one go.


(I'm writing this from the perspective of 'Apprentice' professionals or 
a ComSc student - with any/all due apologies and respect to the OP)


There is much virtue in saying that every Python routine should solve 
one problem (and only one!), and do that well. Similarly, the scientific 
method as applied to software development is to break each problem into 
smaller, more manageable problems (per ardua) - and thus, more 
recognisable solutions (and we're back to me banging-the-drum of 
readability).

Here's the problem-solution:

     def validate_password( attempt:str )->bool:
         ...

(Oh yeah, wow!)

Obviously(!) this (larger) routine will contain more (smaller, more 
manageable) routines. We can follow the format, exactly as outlined in 
the specification (or homework assignment, as appropriate):

 > Minimum 8 characters.

     def validate_length( rule:int, attempt:str )->bool:

 > The alphabets must be between [a-z]

     def validate_lower_case( attempt:str )->bool:
         # see note, below

 > At least one alphabet should be of Upper Case [A-Z]

     def validate_upper_case( attempt:str )->bool:
         # also, see note, below

 > At least 1 number or digit between [0-9].

     def validate_numeric( attempt:str )->bool:
         # again, see note, below

 > At least 1 character from [ _ or @ or $ ].

     def validate_specials( rule:Set, attempt:str )->bool:


There were five specifications, so there are five (sub) routines, called 
in-turn by validate_password() (a "decision ladder") - with a fast-drop, 
should you wish.


Hang-on though, look at how much 'work' is involved, compared with a 
single line of RegEx! Why go to such bother? There's several reasons.


Notice how the spec has become code? "Readability" is not merely the 
appearance and communication-quality of one's code, but the transfer of 
ideas across levels, or layers, of detail!


Notice that the above have a parameter "rule". Why?
(and that's not (only) the question: "why don't we encode these as 
constants within the function?")

If you've 'been around' for a while, you will have noticed that password 
rules keep changing, over time, presuming that becoming more 'strict', 
will make the system more secure.
(am not going to discuss the hope of solving (largely) social problems 
with technological solutions!)

What would be the impact of a 'make it strict-er' business-rule change 
(specification) on the one-line RegEx solution? Persisting with the 
long-way around:-

A frequent call is to increase the minimum-length of passwords. How 
could we do this? Using RegEx, adjust the counter - but which part is 
the 'counter'?

Alternately, here, reading the code we find validate_length() (or the 
documentation where "rule" is defined/given its value) and change the 
value of the integer. QED!
(and by "QED" I mean: this is a job which could be given to the newest 
of Junior Programmers, with a high confidence of (rapid) success)

Similarly, in the above structure, validate_specials() expects to be 
given a 'rule' which is currently:

     { '[', '_', '@', '$', ']', }

How easy would it be to add another character, eg "#" or "?"; when your 
system goes international and is being used by folk with 
European-variant keyboards? Is extending the set easier (and more likely 
to retain fidelity) than fiddling with a RegEx?


[and here's the note]

If our ambitions include dreams of 'world domination', then we can 
extend exactly the same idea of "rule" to the other three routines! 
Whilst we 'start' with (say) the ASCII character definitions of a-z, we 
will *be able* to extend into accented characters such as "?"  - which 
really would promote us to take a r?le on the world-stage.
(hah!)


 From a 'business'/users' perspective: note that the five routines could 
easily be extended should further business-rules be demanded.

 From a code-perspective: note that either "in" could be used to detect 
presence (but not so easily 'count', eg minimum of two lower-case 
letters), or we could persist with RegEx solution(s) - in which case, by 
breaking the larger problem into smaller ones, the RegEx 
complexity-level falls to that which mere-mortals may comprehend!


Now let's stoop to allowing that although programmers are *the* most 
important people in the world, we should consider our users - just once 
in a while. Thus, lets consider UX ("User Experience"). Most of us hate 
situations when we are asked to furnish a password but 'get it wrong' - 
particularly those sites which fail to tell us 'the rules' BEFORE we 
offer our preference!

If we're going to be nice to our users, from where do we express these 
"rules"? If the rule is hard-coded, then the user-advice must also be 
hard-coded - and what do we say about having 'the same code' in multiple 
locations? (see also "DRY principle"). How could one state "the rules" 
*once*, and in such a fashion that they can be used for UX output and a 
RegEx?

Second UX-consideration (and its a 'biggie'!): if a password 'fails', 
how can we take the 'result' from a large and complex RegEx, and explain 
to the user which [multiple] of the five requirements was/were not met? 
A failure in the RegEx above tells the system not to proceed, but 
doesn't tell the user is a letter is missing, a digit, ...


RegEx is extremely powerful, but 'power' is seductive - just because we 
can do something doesn't make it a good idea! The Spiderman rule applies...
-- 
Regards =dn

From 2QdxY4RzWzUUiLuE at potatochowder.com  Wed Dec 23 18:20:25 2020
From: 2QdxY4RzWzUUiLuE at potatochowder.com (2QdxY4RzWzUUiLuE at potatochowder.com)
Date: Wed, 23 Dec 2020 17:20:25 -0600
Subject: using regex for password validation
In-Reply-To: <36c7f24e-5410-26a2-6070-74336e71ffdb@DancesWithMice.info>
References: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
 <36c7f24e-5410-26a2-6070-74336e71ffdb@DancesWithMice.info>
Message-ID: <X+PQuXXC61A1i11Z@scrozzle>

On 2020-12-24 at 11:41:15 +1300,
dn via Python-list <python-list at python.org> wrote:

> On 24/12/2020 06:03, Sadaka Technology wrote:
> > hello guys,
> > 
> > I have this pattern for password validation (regex):

[...]

> > passwordpattern = "^(?=.[a-z])(?=.[A-Z])(?=.\d)(?=.[@$])[A-Za-z\d@$!%?&]{8,}.$"
> > 
> > my only issue is that I want to add the symbol () and symbol(.) in
> > the pattern where only it accepts $ and @, I tried adding generally
> > like [@_$] not working

[...]

Is it my imagination, or does a password in which the only lower case
letter is at the beginning fail?

> Contrarily, a RegEx may be quite the wrong tool for the job. Partially
> because such expressions are difficult to understand - either someone
> else's code or my own from the proverbial six-months back(!); and
> partially here we're attempting to solve multiple problems in one go.

"[M]ay be quite"?  You are far too kind, dn.

> If our ambitions include dreams of 'world domination', then we can
> extend exactly the same idea of "rule" to the other three routines!
> Whilst we 'start' with (say) the ASCII character definitions of a-z,
> we will *be able* to extend into accented characters such as "?" -
> which really would promote us to take a r?le on the world-stage.
> (hah!)

If you're going to wander out of ASCII, then don't forget to address
Unicode confusables.  Nothing is more embarrassing than scribbling your
complicated password on a sticky note and then not being able to tell
the o's from the ?'s.  ;-)

> If we're going to be nice to our users, from where do we express these
> "rules"? If the rule is hard-coded, then the user-advice must also be
> hard-coded - and what do we say about having 'the same code' in
> multiple locations? (see also "DRY principle"). How could one state
> "the rules" *once*, and in such a fashion that they can be used for UX
> output and a RegEx?

That's the beauty of a regular expression:  it's both human and computer
readable.  Just show the user the regular expression(s) you used.  Oh,
wait.  Sorry.  Scratch that.

Thanks, dn, for saying all of that (including what I snipped) out loud.

From rosuav at gmail.com  Wed Dec 23 18:25:27 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 24 Dec 2020 10:25:27 +1100
Subject: using regex for password validation
In-Reply-To: <36c7f24e-5410-26a2-6070-74336e71ffdb@DancesWithMice.info>
References: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
 <36c7f24e-5410-26a2-6070-74336e71ffdb@DancesWithMice.info>
Message-ID: <CAPTjJmp9Gi2LK35VZQ349UGCuXCrR-NttTggNgsnAp+ikGVmLA@mail.gmail.com>

On Thu, Dec 24, 2020 at 9:42 AM dn via Python-list
<python-list at python.org> wrote:
> Hang-on though, look at how much 'work' is involved, compared with a
> single line of RegEx! Why go to such bother? There's several reasons.

Good question! Look at this alternative:

def validate_password(attempt):
    return len(attempt) >= 11

Wow! So much easier. Only one function needed AND it's more secure!

> A frequent call is to increase the minimum-length of passwords. How
> could we do this? Using RegEx, adjust the counter - but which part is
> the 'counter'?

In my example here, it's pretty easy to find!

> If our ambitions include dreams of 'world domination', then we can
> extend exactly the same idea of "rule" to the other three routines!
> Whilst we 'start' with (say) the ASCII character definitions of a-z, we
> will *be able* to extend into accented characters such as "?"  - which
> really would promote us to take a r?le on the world-stage.
> (hah!)

Wow! It wins on that too! And even better - it counts Cyrillic letters
as letters, it counts Greek letters as letters, and it counts Arabic
letters as letters too! Isn't it so much easier than a regex?

> If we're going to be nice to our users, from where do we express these
> "rules"? If the rule is hard-coded, then the user-advice must also be
> hard-coded - and what do we say about having 'the same code' in multiple
> locations? (see also "DRY principle"). How could one state "the rules"
> *once*, and in such a fashion that they can be used for UX output and a
> RegEx?

Very very good point. I think "Passwords must be at least eleven
characters long" is a problem, because you would need to *manually*
translate the number "11" into the word "eleven". So the best way
would be to use "Passwords must be at least {minlength} characters
long" and then you know that it's going to correlate.

> Second UX-consideration (and its a 'biggie'!): if a password 'fails',
> how can we take the 'result' from a large and complex RegEx, and explain
> to the user which [multiple] of the five requirements was/were not met?
> A failure in the RegEx above tells the system not to proceed, but
> doesn't tell the user is a letter is missing, a digit, ...
>

True, very true. Once again, a win for simplicity: with only one rule,
it's easy to know which one you ran up against.

ChrisA

From rosuav at gmail.com  Wed Dec 23 18:29:30 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 24 Dec 2020 10:29:30 +1100
Subject: using regex for password validation
In-Reply-To: <X+PQuXXC61A1i11Z@scrozzle>
References: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
 <36c7f24e-5410-26a2-6070-74336e71ffdb@DancesWithMice.info>
 <X+PQuXXC61A1i11Z@scrozzle>
Message-ID: <CAPTjJmpTDqLaMwHQZpgBfR1bRNrjv4GU4ocWKMJTrq4SpWmTxQ@mail.gmail.com>

On Thu, Dec 24, 2020 at 10:21 AM <2QdxY4RzWzUUiLuE at potatochowder.com> wrote:
> If you're going to wander out of ASCII, then don't forget to address
> Unicode confusables.  Nothing is more embarrassing than scribbling your
> complicated password on a sticky note and then not being able to tell
> the o's from the ?'s.  ;-)

TBH I don't think that's really our consideration. My recommendation
is: First do a basic Unicode normalization (probably NFC, but there
are good arguments for NFD instead), then just use it as-is.
Everything else is the user's choice. And you shouldn't ever have to
worry about a maximum length; after any checks such as "both passwords
must be the same" (on account creation), the only thing you'll need to
do is encode it UTF-8 and hand it to bcrypt.

But by using simpler password requirements (an 11-character minimum is
good in 2020, but maybe in the future you might want to extend that to
12), you reduce the temptation to use confusable letters in it.
Context is everything.

ChrisA

From PythonList at DancesWithMice.info  Wed Dec 23 20:28:24 2020
From: PythonList at DancesWithMice.info (dn)
Date: Thu, 24 Dec 2020 14:28:24 +1300
Subject: using regex for password validation
In-Reply-To: <X+PQuXXC61A1i11Z@scrozzle>
References: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
 <36c7f24e-5410-26a2-6070-74336e71ffdb@DancesWithMice.info>
 <X+PQuXXC61A1i11Z@scrozzle>
Message-ID: <0988d584-6fea-a95a-610a-4c713093e313@DancesWithMice.info>

On 24/12/2020 12:20, 2QdxY4RzWzUUiLuE at potatochowder.com wrote:
> On 2020-12-24 at 11:41:15 +1300,
> dn via Python-list <python-list at python.org> wrote:
>> On 24/12/2020 06:03, Sadaka Technology wrote:
>>> hello guys,
>>>
>>> I have this pattern for password validation (regex):
> 
> [...]

> Is it my imagination, or does a password in which the only lower case
> letter is at the beginning fail?

As mentioned, I don't use RegEx so-often and rely upon a crib-sheet. 
What I could?should have added, is that there are many web-sites which 
enable one to enter a RegEx and some sample data, for immediate 
verification. Very handy!


>> Contrarily, a RegEx may be quite the wrong tool for the job. Partially
>> because such expressions are difficult to understand - either someone
>> else's code or my own from the proverbial six-months back(!); and
>> partially here we're attempting to solve multiple problems in one go.
> 
> "[M]ay be quite"?  You are far too kind, dn.

The people on this list often help me, so...


Whereas I prefer to use str.functions, others may have their own 
opinion. To some degree it's one of those 'horses for courses' 
situations - and as illustrated, if the specs are tightened a bit 
further, it may well be that a 'minimum of two upper-case characters' 
rule would be easier to check with a RegEx!


>> If our ambitions include dreams of 'world domination', then we can
>> extend exactly the same idea of "rule" to the other three routines!
>> Whilst we 'start' with (say) the ASCII character definitions of a-z,
>> we will *be able* to extend into accented characters such as "?" -
>> which really would promote us to take a r?le on the world-stage.
>> (hah!)
> 
> If you're going to wander out of ASCII, then don't forget to address
> Unicode confusables.  Nothing is more embarrassing than scribbling your
> complicated password on a sticky note and then not being able to tell
> the o's from the ?'s.  ;-)

?k!


>> If we're going to be nice to our users, from where do we express these
>> "rules"? If the rule is hard-coded, then the user-advice must also be
>> hard-coded - and what do we say about having 'the same code' in
>> multiple locations? (see also "DRY principle"). How could one state
>> "the rules" *once*, and in such a fashion that they can be used for UX
>> output and a RegEx?
> 
> That's the beauty of a regular expression:  it's both human and computer
> readable.  Just show the user the regular expression(s) you used.  Oh,
> wait.  Sorry.  Scratch that.
> 
> Thanks, dn, for saying all of that (including what I snipped) out loud.


I've finished 'official work' for the year - compliments of the season!
-- 
Regards =dn

From PythonList at DancesWithMice.info  Wed Dec 23 20:54:26 2020
From: PythonList at DancesWithMice.info (dn)
Date: Thu, 24 Dec 2020 14:54:26 +1300
Subject: using regex for password validation
In-Reply-To: <CAPTjJmp9Gi2LK35VZQ349UGCuXCrR-NttTggNgsnAp+ikGVmLA@mail.gmail.com>
References: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
 <36c7f24e-5410-26a2-6070-74336e71ffdb@DancesWithMice.info>
 <CAPTjJmp9Gi2LK35VZQ349UGCuXCrR-NttTggNgsnAp+ikGVmLA@mail.gmail.com>
Message-ID: <4245998a-d696-d6b6-c1ff-9702fd6fd641@DancesWithMice.info>

On 24/12/2020 12:25, Chris Angelico wrote:
> On Thu, Dec 24, 2020 at 9:42 AM dn via Python-list
> <python-list at python.org> wrote:
>> Hang-on though, look at how much 'work' is involved, compared with a
>> single line of RegEx! Why go to such bother? There's several reasons.
> 
> Good question! Look at this alternative:
> 
> def validate_password(attempt):
>      return len(attempt) >= 11
> 
> Wow! So much easier. Only one function needed AND it's more secure!

You and I have discussed such topics before @Chris. However, we both 
know that if the client specifies something (and we can't moderate 
such), we deliver accordingly - per Alfred Lord Tennyson.

What we don't know is the OP's wiggle-room with his/her 'client' - which 
may be zero if the 'client' is an assignment-grade!

However, the discussion 'beyond' the OP's immediate question is very 
necessary!


>> A frequent call is to increase the minimum-length of passwords. How
>> could we do this? Using RegEx, adjust the counter - but which part is
>> the 'counter'?
> 
> In my example here, it's pretty easy to find!

In a 'global definition' block or buried in the code-base?


>> If our ambitions include dreams of 'world domination', then we can
>> extend exactly the same idea of "rule" to the other three routines!
>> Whilst we 'start' with (say) the ASCII character definitions of a-z, we
>> will *be able* to extend into accented characters such as "?"  - which
>> really would promote us to take a r?le on the world-stage.
>> (hah!)
> 
> Wow! It wins on that too! And even better - it counts Cyrillic letters
> as letters, it counts Greek letters as letters, and it counts Arabic
> letters as letters too! Isn't it so much easier than a regex?

- but wouldn't you agree that

     attempt == "x"*12

is no safer than "xxxx"? So, maybe a length-rule without any other 
consideration is 'weak-beer'?

(speaking of beer, and for the benefit of non-Australians, and people 
everywhere who did learn their abc-s, "xxxx" is how @Chris spells "beer"!)
NB probably not suitable for office-viewing: 
https://www.youtube.com/watch?v=mtwkDGlpWJk - cheers @Chris!

Speaking of Australian humor:-


>> If we're going to be nice to our users, from where do we express these
>> "rules"? If the rule is hard-coded, then the user-advice must also be
>> hard-coded - and what do we say about having 'the same code' in multiple
>> locations? (see also "DRY principle"). How could one state "the rules"
>> *once*, and in such a fashion that they can be used for UX output and a
>> RegEx?
> 
> Very very good point. I think "Passwords must be at least eleven
> characters long" is a problem, because you would need to *manually*
> translate the number "11" into the word "eleven". So the best way
> would be to use "Passwords must be at least {minlength} characters
> long" and then you know that it's going to correlate.

Now you're just being plain mischievous!


>> Second UX-consideration (and its a 'biggie'!): if a password 'fails',
>> how can we take the 'result' from a large and complex RegEx, and explain
>> to the user which [multiple] of the five requirements was/were not met?
>> A failure in the RegEx above tells the system not to proceed, but
>> doesn't tell the user is a letter is missing, a digit, ...
> 
> True, very true. Once again, a win for simplicity: with only one rule,
> it's easy to know which one you ran up against.

The 'one rule' I try to live-by, is not to attempt 'important stuff' in 
which I have insufficient knowledge*. Rather than strain my brain (and 
spend an inordinate amount of time) deciding if/how to authenticate and 
authorise users, and then coding same, I'd rather pass the task to a 
TechSec specialist!

* which *may* make me seem less like Dilbert, and more Wally
https://en.wikipedia.org/wiki/List_of_Dilbert_characters
-- 
Regards =dn

From rosuav at gmail.com  Wed Dec 23 21:17:25 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 24 Dec 2020 13:17:25 +1100
Subject: using regex for password validation
In-Reply-To: <4245998a-d696-d6b6-c1ff-9702fd6fd641@DancesWithMice.info>
References: <f454b204-432f-412e-a4b3-7ddff821eec2n@googlegroups.com>
 <36c7f24e-5410-26a2-6070-74336e71ffdb@DancesWithMice.info>
 <CAPTjJmp9Gi2LK35VZQ349UGCuXCrR-NttTggNgsnAp+ikGVmLA@mail.gmail.com>
 <4245998a-d696-d6b6-c1ff-9702fd6fd641@DancesWithMice.info>
Message-ID: <CAPTjJmoN-fTtNGxiwHOF2pu7Xv_AwqOoNE+NFj3rt3CsFJSVhg@mail.gmail.com>

On Thu, Dec 24, 2020 at 12:56 PM dn via Python-list
<python-list at python.org> wrote:
>
> On 24/12/2020 12:25, Chris Angelico wrote:
> > On Thu, Dec 24, 2020 at 9:42 AM dn via Python-list
> > <python-list at python.org> wrote:
> >> Hang-on though, look at how much 'work' is involved, compared with a
> >> single line of RegEx! Why go to such bother? There's several reasons.
> >
> > Good question! Look at this alternative:
> >
> > def validate_password(attempt):
> >      return len(attempt) >= 11
> >
> > Wow! So much easier. Only one function needed AND it's more secure!
>
> You and I have discussed such topics before @Chris. However, we both
> know that if the client specifies something (and we can't moderate
> such), we deliver accordingly - per Alfred Lord Tennyson.
>
> What we don't know is the OP's wiggle-room with his/her 'client' - which
> may be zero if the 'client' is an assignment-grade!

The OP said:

> I want these rules to be applied:

That means one of two things. Either it's a homework assignment and
s/he is dishonestly pretending that it isn't one, or the OP invented
the rules. There's nothing about "my client asked me to guard with
these exact rules and I want to use a regex so I can have the exact
same validation done by the web browser before it gets sent to the
server". Don't assume justifications that aren't supported by
evidence.

> >> A frequent call is to increase the minimum-length of passwords. How
> >> could we do this? Using RegEx, adjust the counter - but which part is
> >> the 'counter'?
> >
> > In my example here, it's pretty easy to find!
>
> In a 'global definition' block or buried in the code-base?

Either way would work. Either way is easier than digging through a regex.

> >> If our ambitions include dreams of 'world domination', then we can
> >> extend exactly the same idea of "rule" to the other three routines!
> >> Whilst we 'start' with (say) the ASCII character definitions of a-z, we
> >> will *be able* to extend into accented characters such as "?"  - which
> >> really would promote us to take a r?le on the world-stage.
> >> (hah!)
> >
> > Wow! It wins on that too! And even better - it counts Cyrillic letters
> > as letters, it counts Greek letters as letters, and it counts Arabic
> > letters as letters too! Isn't it so much easier than a regex?
>
> - but wouldn't you agree that
>
>      attempt == "x"*12
>
> is no safer than "xxxx"? So, maybe a length-rule without any other
> consideration is 'weak-beer'?

Would you say that "12345Aa$" is a weak password, despite fitting the
requirements? What if the password is the person's name? What if the
password hint is "the password is 'Sw at rdf1sh'"? It's not our job to
stop the user from creating a weak password - just to encourage the
use of better passwords.

A length rule on its own is sufficient to cover a lot of cases, and no
regex is sufficient to cover all cases.

> (speaking of beer, and for the benefit of non-Australians, and people
> everywhere who did learn their abc-s, "xxxx" is how @Chris spells "beer"!)
> NB probably not suitable for office-viewing:
> https://www.youtube.com/watch?v=mtwkDGlpWJk - cheers @Chris!

Actually I don't, that's a myth :)

ChrisA

From stackflowauto at gmail.com  Fri Dec 25 20:26:50 2020
From: stackflowauto at gmail.com (stackf...@gmail.com)
Date: Fri, 25 Dec 2020 17:26:50 -0800 (PST)
Subject: unable to launch python3.8 -m idlelib.idle
Message-ID: <6c87291f-108c-4b14-957e-9dd000e3b725n@googlegroups.com>

unable to launch python3.8 -m idlelib.idle. getting below error msg. I am new to python. kindly help.

python3.8 -m idlelib.idle

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/idlelib/idle.py", line 13, in <module>
    from idlelib.pyshell import main  # This is subject to change
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/idlelib/pyshell.py", line 56, in <module>
    from idlelib import rpc
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/idlelib/rpc.py", line 73, in <module>
    class RPCServer(socketserver.TCPServer):
AttributeError: module 'socketserver' has no attribute 'TCPServer'

From tjreedy at udel.edu  Fri Dec 25 21:33:31 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Fri, 25 Dec 2020 21:33:31 -0500
Subject: unable to launch python3.8 -m idlelib.idle
In-Reply-To: <6c87291f-108c-4b14-957e-9dd000e3b725n@googlegroups.com>
References: <6c87291f-108c-4b14-957e-9dd000e3b725n@googlegroups.com>
Message-ID: <rs67dt$km4$1@ciao.gmane.io>

On 12/25/2020 8:26 PM, stackf... at gmail.com wrote:
> unable to launch python3.8 -m idlelib.idle. getting below error msg. I am new to python. kindly help.

One should include OS with failure questions and perhaps how installed. 
  Appears to be macOS, installed with ???

> python3.8 -m idlelib.idle

For 3.x, '.idle' is not needed.

>    File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/idlelib/rpc.py", line 73, in <module>
>      class RPCServer(socketserver.TCPServer):
> AttributeError: module 'socketserver' has no attribute 'TCPServer'

https://docs.python.org/3.8/library/socketserver.html#socketserver.TCPServer
It is very much supposed to, so you installation seems faulty.  I am 
running IDLE on macOS with 3.8, 3.9, and 3.10, installed with the 
python.org installer.

This is one of the few circumstances for which I suggest re-installing.

-- 
Terry Jan Reedy


From rosuav at gmail.com  Fri Dec 25 23:44:28 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 26 Dec 2020 15:44:28 +1100
Subject: unable to launch python3.8 -m idlelib.idle
In-Reply-To: <rs67dt$km4$1@ciao.gmane.io>
References: <6c87291f-108c-4b14-957e-9dd000e3b725n@googlegroups.com>
 <rs67dt$km4$1@ciao.gmane.io>
Message-ID: <CAPTjJmpVsgfVj6kZqBe68zTMxavmfr2E=BOHPaW-412t6ekDmQ@mail.gmail.com>

On Sat, Dec 26, 2020 at 2:32 PM Terry Reedy <tjreedy at udel.edu> wrote:
>
> On 12/25/2020 8:26 PM, stackf... at gmail.com wrote:
> > unable to launch python3.8 -m idlelib.idle. getting below error msg. I am new to python. kindly help.
>
> One should include OS with failure questions and perhaps how installed.
>   Appears to be macOS, installed with ???
>
> > python3.8 -m idlelib.idle
>
> For 3.x, '.idle' is not needed.
>
> >    File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/idlelib/rpc.py", line 73, in <module>
> >      class RPCServer(socketserver.TCPServer):
> > AttributeError: module 'socketserver' has no attribute 'TCPServer'
>
> https://docs.python.org/3.8/library/socketserver.html#socketserver.TCPServer
> It is very much supposed to, so you installation seems faulty.  I am
> running IDLE on macOS with 3.8, 3.9, and 3.10, installed with the
> python.org installer.
>
> This is one of the few circumstances for which I suggest re-installing.
>

Or seeing if you have a socketserver.py in the current directory.

ChrisA

From rshepard at appl-ecosys.com  Sat Dec 26 12:13:13 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Sat, 26 Dec 2020 09:13:13 -0800 (PST)
Subject: Installing python3 modules
Message-ID: <alpine.LNX.2.20.2012260904500.4833@salmo.appl-ecosys.com>

Running Slackware-14.2/x86_64 here. I'm trying to learn if any installed
applications are still dependent on Python2 (version 2.7.17 installed) as
its EOL is this coming Thursday and I want to clean out all Python2 modules
and replace them with their Python3 versions (3.9 installed here). This
raises several questions.

First, I had to remove, reinstall, and upgrade pip. The pip web page says
it's compatible with python2 and 3 through 3.8. Does this mean it still does
not support Python3.9?

Second, pip installed itself in /usr/lib64/python2/site-packages/, not the
python3.9/site-packages/ directory. There's not a pip3 so how do I get pip
and all other python modules in the python3.9/site-packages/ directory?

As an occasional coder (for my own business uses) I'm far from an advanced
python user.

TIA,

Rich

From barry at barrys-emacs.org  Sat Dec 26 12:56:47 2020
From: barry at barrys-emacs.org (Barry Scott)
Date: Sat, 26 Dec 2020 17:56:47 +0000
Subject: Installing python3 modules
In-Reply-To: <alpine.LNX.2.20.2012260904500.4833@salmo.appl-ecosys.com>
References: <alpine.LNX.2.20.2012260904500.4833@salmo.appl-ecosys.com>
Message-ID: <8BBA95A7-0515-4F30-B6E2-C332B5499F0E@barrys-emacs.org>



> On 26 Dec 2020, at 17:13, Rich Shepard <rshepard at appl-ecosys.com> wrote:
> 
> Running Slackware-14.2/x86_64 here. I'm trying to learn if any installed
> applications are still dependent on Python2 (version 2.7.17 installed) as
> its EOL is this coming Thursday and I want to clean out all Python2 modules
> and replace them with their Python3 versions (3.9 installed here). This
> raises several questions.
> 
> First, I had to remove, reinstall, and upgrade pip. The pip web page says
> it's compatible with python2 and 3 through 3.8. Does this mean it still does
> not support Python3.9?

It works great with 3.9. which web psge did you see the claim on?

Barry

> 
> Second, pip installed itself in /usr/lib64/python2/site-packages/, not the
> python3.9/site-packages/ directory. There's not a pip3 so how do I get pip
> and all other python modules in the python3.9/site-packages/ directory?
> 
> As an occasional coder (for my own business uses) I'm far from an advanced
> python user.
> 
> TIA,
> 
> Rich
> -- 
> https://mail.python.org/mailman/listinfo/python-list
> 


From mats at wichmann.us  Sat Dec 26 13:50:16 2020
From: mats at wichmann.us (Mats Wichmann)
Date: Sat, 26 Dec 2020 11:50:16 -0700
Subject: Installing python3 modules
In-Reply-To: <alpine.LNX.2.20.2012260904500.4833@salmo.appl-ecosys.com>
References: <alpine.LNX.2.20.2012260904500.4833@salmo.appl-ecosys.com>
Message-ID: <9ec67d43-e010-c858-0df7-a52926b6fa06@wichmann.us>

On 12/26/20 10:13 AM, Rich Shepard wrote:
> Running Slackware-14.2/x86_64 here. I'm trying to learn if any installed
> applications are still dependent on Python2 (version 2.7.17 installed) as
> its EOL is this coming Thursday and I want to clean out all Python2 modules
> and replace them with their Python3 versions (3.9 installed here). This
> raises several questions.
> 
> First, I had to remove, reinstall, and upgrade pip. The pip web page says
> it's compatible with python2 and 3 through 3.8. Does this mean it still 
> does
> not support Python3.9?

pip supports 3.9 fine, and is just about to lose support for 2.x entirely.

> 
> Second, pip installed itself in /usr/lib64/python2/site-packages/, not the
> python3.9/site-packages/ directory. There's not a pip3 so how do I get pip
> and all other python modules in the python3.9/site-packages/ directory?

this sounds like a Slack packaging issue, have you checked with 
appropriate forums_

From rshepard at appl-ecosys.com  Sat Dec 26 14:29:30 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Sat, 26 Dec 2020 11:29:30 -0800 (PST)
Subject: Installing python3 modules
In-Reply-To: <9ec67d43-e010-c858-0df7-a52926b6fa06@wichmann.us>
References: <alpine.LNX.2.20.2012260904500.4833@salmo.appl-ecosys.com>
 <9ec67d43-e010-c858-0df7-a52926b6fa06@wichmann.us>
Message-ID: <alpine.LNX.2.20.2012261127510.4833@salmo.appl-ecosys.com>

On Sat, 26 Dec 2020, Mats Wichmann wrote:

> pip supports 3.9 fine, and is just about to lose support for 2.x entirely.

Mats,

Yes, it does.

> this sounds like a Slack packaging issue, have you checked with appropriate 
> forums_

It's apparently a local issue: my python3 packages ended up in
/usr/lib/python2.7/site-packages/ rather than
//usr/lib64/python3.9/site-packages/. I'm rebuilding all installed python3
packages.

Stay well,

Rich

From sersadaka1 at outlook.com  Sat Dec 26 07:03:40 2020
From: sersadaka1 at outlook.com (Sadaka Technology)
Date: Sat, 26 Dec 2020 04:03:40 -0800 (PST)
Subject: Pyrebase auth
Message-ID: <a9af41c3-3ae5-470a-a714-d3c08491cf73n@googlegroups.com>

I am using signup method:

user_signup = auth.create_user_with_email_and_password(email, password)

and my firebase rules are:

{
  "rules": {
    ".read": false,
    ".write": false,
      "$localId":  {
        ".write": "auth.uid === $localId",
        ".read": "auth.uid === $localId"
      }      
  }
}

I used:

data = {"item1":"hat","item2":"car"}
results = db.child("users").update(data, user['idToken'])

the only way to patch (update) is to use:
    ".read": true,
    ".write": true,

which means that anyone can read or write in my database where I only want the user to write or read if his idtoken or localid is authorized, even if data is outside his region for ex:

database:

"number_of_users":"2"

"userlocalid":
         {"item1":"hat"}
         {"item2":"car"}

From rshepard at appl-ecosys.com  Sat Dec 26 13:33:54 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Sat, 26 Dec 2020 10:33:54 -0800 (PST)
Subject: Installing python3 modules
In-Reply-To: <8BBA95A7-0515-4F30-B6E2-C332B5499F0E@barrys-emacs.org>
References: <alpine.LNX.2.20.2012260904500.4833@salmo.appl-ecosys.com>
 <8BBA95A7-0515-4F30-B6E2-C332B5499F0E@barrys-emacs.org>
Message-ID: <alpine.LNX.2.20.2012261033020.4833@salmo.appl-ecosys.com>

On Sat, 26 Dec 2020, Barry Scott wrote:

> It works great with 3.9. which web psge did you see the claim on?

Barry,

I don't recall which pip3 installation page it was. But I used 'python3
get-pip.py' and that worked.

Stay well,

Rich

From tjreedy at udel.edu  Sat Dec 26 13:51:02 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Sat, 26 Dec 2020 13:51:02 -0500
Subject: Installing python3 modules
In-Reply-To: <alpine.LNX.2.20.2012260904500.4833@salmo.appl-ecosys.com>
References: <alpine.LNX.2.20.2012260904500.4833@salmo.appl-ecosys.com>
Message-ID: <rs80mn$glr$1@ciao.gmane.io>

On 12/26/2020 12:13 PM, Rich Shepard wrote:
> Running Slackware-14.2/x86_64 here. I'm trying to learn if any installed
> applications are still dependent on Python2 (version 2.7.17 installed) as
> its EOL is this coming Thursday and I want to clean out all Python2 modules
> and replace them with their Python3 versions (3.9 installed here). This
> raises several questions.
> 
> First, I had to remove, reinstall, and upgrade pip. The pip web page says
> it's compatible with python2 and 3 through 3.8. Does this mean it still 
> does
> not support Python3.9?
> 
> Second, pip installed itself in /usr/lib64/python2/site-packages/, not the
> python3.9/site-packages/ directory.

Pip is a python code run by a python interpreter.  It installs itself in 
the site-packages of the python you use to run it.  'pythonx -m 
ensurepip' will make sure some pip is available for pythonx.  'pythonx 
-m pip' will then run the pythonx pip and manipulate the contents of its 
site-packages.

> There's not a pip3

Separate 'pip' executables can be ambiguous as to which python they will 
invoke.  Some people consider them a mistake.

> so how do I get pip
> and all other python modules in the python3.9/site-packages/ directory?

See above.  Run pip with python3.9, however that is spelled on a 
particular system.  I don't know if all the modules you want have 
versions compatible with 3.9, but anything actively maintained should. 
The 3.8 versions of pure python modules will often run with 3.9 without 
change, even if not yet certified to do so by the authors.

-- 
Terry Jan Reedy


From rshepard at appl-ecosys.com  Sat Dec 26 14:40:31 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Sat, 26 Dec 2020 11:40:31 -0800 (PST)
Subject: Installing python3 modules
In-Reply-To: <rs80mn$glr$1@ciao.gmane.io>
References: <alpine.LNX.2.20.2012260904500.4833@salmo.appl-ecosys.com>
 <rs80mn$glr$1@ciao.gmane.io>
Message-ID: <alpine.LNX.2.20.2012261137440.4833@salmo.appl-ecosys.com>

On Sat, 26 Dec 2020, Terry Reedy wrote:

> Separate 'pip' executables can be ambiguous as to which python they will
> invoke. Some people consider them a mistake.

Terry,

Until there's no more python2 it can remain confusing.

I found part, if not all, of my problem. The SlackBuild scripts for
multi-version python modules (such as Pygment) have install instructions for
both python2 and python3, in that order. Since there's a python2 version
installed the script installs Pygment (and others) there and not also in the
python3 site-packages/ directory.

>> so how do I get pip
>> and all other python modules in the python3.9/site-packages/ directory?

Fixed.

Thanks,

Rich

From songbird at anthive.com  Sat Dec 26 19:26:26 2020
From: songbird at anthive.com (songbird)
Date: Sat, 26 Dec 2020 19:26:26 -0500
Subject: Debian testing and virtual environment error message
Message-ID: <iu0lbh-b73.ln1@anthive.com>


  Simlar to Rich's asking about how to deal with python3.9
I'm not able to to get my virtual environment set up to work
now and I'm not sure how to go about fixing this.

  As it is testing I may have broken it somehow but I do not
know how to fix this.

  I asked on the Debian user mailing list and nobody had any
response/ideas.

  Note, this isn't a production system and I don't mind it
being temporarily broken, but I also would like to know what
is going on and how to fix this sort of thing.

  I do have python-is-python3 package installed and there are 
no python2 programs anywhere on this system that I know of.


  When i run the command:

=====
$ cd /home/me/src/salsa
$ python -m venv env

  setting up virtual environment /home/me/src/salsa/env
The virtual environment was not created successfully because ensurepip is not
available.  On Debian/Ubuntu systems, you need to install the python3-venv
package using the following command.

    apt-get install python3-venv

You may need to use sudo with that command.  After installing the python3-venv
package, recreate your virtual environment.

Failing command: ['/home/me/src/salsa/env/bin/python', '-Im', 'ensurepip', '--upgrade', '--default-pip']

=====


  The package mentioned is installed:


=====

$ dpkg -l | grep python3-venv
ii  python3-venv                         3.9.0-4                        amd64        pyvenv-3 binary for python3 (default python3 version)

=====

  Also the following looks interesting but I'm not sure why there
is no 3.9 version available:

=====
$ dpkg -l | grep python-is
ii  python-is-python3                    3.8.6-3                        all          symlinks /usr/bin/python to python3
# su -
  entered password
# apt-get install python-is-python3 -t unstable
Reading package lists... Done
Building dependency tree       
Reading state information... Done
python-is-python3 is already the newest version (3.8.6-3).
0 upgraded, 0 newly installed, 0 to remove and 250 not upgraded.

=====

  any ideas?  :)  thanks!


  songbird

From rosuav at gmail.com  Sat Dec 26 20:58:33 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 27 Dec 2020 12:58:33 +1100
Subject: Debian testing and virtual environment error message
In-Reply-To: <iu0lbh-b73.ln1@anthive.com>
References: <iu0lbh-b73.ln1@anthive.com>
Message-ID: <CAPTjJmreyiLJNj_V3W1QkTOwy2wYn4Z9f5MZZpsuPFQ084E0-Q@mail.gmail.com>

On Sun, Dec 27, 2020 at 11:31 AM songbird <songbird at anthive.com> wrote:
>
>
>   Simlar to Rich's asking about how to deal with python3.9
> I'm not able to to get my virtual environment set up to work
> now and I'm not sure how to go about fixing this.
>
>   As it is testing I may have broken it somehow but I do not
> know how to fix this.
>
>   I asked on the Debian user mailing list and nobody had any
> response/ideas.
>
>   Note, this isn't a production system and I don't mind it
> being temporarily broken, but I also would like to know what
> is going on and how to fix this sort of thing.
>
>   I do have python-is-python3 package installed and there are
> no python2 programs anywhere on this system that I know of.
>

What does this say?

$ which python

ChrisA

From songbird at anthive.com  Sat Dec 26 21:16:30 2020
From: songbird at anthive.com (songbird)
Date: Sat, 26 Dec 2020 21:16:30 -0500
Subject: Debian testing and virtual environment error message
References: <iu0lbh-b73.ln1@anthive.com>
 <CAPTjJmreyiLJNj_V3W1QkTOwy2wYn4Z9f5MZZpsuPFQ084E0-Q@mail.gmail.com>
 <mailman.540.1609034326.7193.python-list@python.org>
Message-ID: <uc7lbh-nq4.ln1@anthive.com>

Chris Angelico wrote:
...
> $ which python


  /usr/bin/python  for both user and root


  looking at /usr/bin it looks like:

lrwxrwxrwx 1 root   root           7 Nov  3 03:20 python -> python3
lrwxrwxrwx 1 root   root           9 Dec  6 05:36 python3 -> python3.9
-rwxr-xr-x 1 root   root     5479736 Dec  8 02:51 python3.9


  thanks,


  songbird

From songbird at anthive.com  Sat Dec 26 22:05:51 2020
From: songbird at anthive.com (songbird)
Date: Sat, 26 Dec 2020 22:05:51 -0500
Subject: Debian testing and virtual environment error message
References: <iu0lbh-b73.ln1@anthive.com>
Message-ID: <f9albh-l75.ln1@anthive.com>

songbird wrote:
...
>   The package mentioned is installed:
>
>
>=====
>
> $ dpkg -l | grep python3-venv
> ii  python3-venv                         3.9.0-4                        amd64        pyvenv-3 binary for python3 (default python3 version)
>

  here is something i missed including in my first post, but i don't
know if this matters:

ii  python3.9-venv                       3.9.1-1                        amd64        Interactive high-level object-oriented language (pyvenv binary, version 3.9)


  songbird

From songbird at anthive.com  Sun Dec 27 10:54:30 2020
From: songbird at anthive.com (songbird)
Date: Sun, 27 Dec 2020 10:54:30 -0500
Subject: Debian testing and virtual environment error message
References: <iu0lbh-b73.ln1@anthive.com>
 <CAPTjJmreyiLJNj_V3W1QkTOwy2wYn4Z9f5MZZpsuPFQ084E0-Q@mail.gmail.com>
 <mailman.540.1609034326.7193.python-list@python.org>
Message-ID: <manmbh-uk5.ln1@anthive.com>

Chris Angelico wrote:

  ok, i got it to work.  i noticed that there was a 3.8
version of distutils that was not upgraded to 3.9 so once
i specifically pulled that in from the unstable Debian
distribution then it upgraded and my creation of a new
virtual environment would work without errors.

  so for some reason there are some python packages in
unstable that had not get gotten to testing.

  thanks for replying.  :)

  for the record this was what i did:

 apt-get install python3-distutils -t unstable
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
   libpython3-all-dbg (3.9.1-1)
   libpython3-all-dev (3.9.1-1)
   libpython3-dbg (3.9.1-1)
   libpython3-dev (3.9.1-1)
   libpython3-stdlib (3.9.1-1)
   python3 (3.9.1-1)
   python3-all (3.9.1-1)
   python3-all-dbg (3.9.1-1)
   python3-all-dev (3.9.1-1)
   python3-dbg (3.9.1-1)
   python3-dev (3.9.1-1)
   python3-lib2to3 (3.9.1-1)
   python3-minimal (3.9.1-1)
   python3-venv (3.9.1-1)
Suggested packages:
   python3-doc (3.9.1-1)
   python3-tk (3.9.1-1)
The following packages will be upgraded:
   libpython3-all-dbg (3.9.0-4 => 3.9.1-1)
   libpython3-all-dev (3.9.0-4 => 3.9.1-1)
   libpython3-dbg (3.9.0-4 => 3.9.1-1)
   libpython3-dev (3.9.0-4 => 3.9.1-1)
   libpython3-stdlib (3.9.0-4 => 3.9.1-1)
   python3 (3.9.0-4 => 3.9.1-1)
   python3-all (3.9.0-4 => 3.9.1-1)
   python3-all-dbg (3.9.0-4 => 3.9.1-1)
   python3-all-dev (3.9.0-4 => 3.9.1-1)
   python3-dbg (3.9.0-4 => 3.9.1-1)
   python3-dev (3.9.0-4 => 3.9.1-1)
   python3-distutils (3.8.6-1 => 3.9.1-1)
   python3-lib2to3 (3.8.6-1 => 3.9.1-1)
   python3-minimal (3.9.0-4 => 3.9.1-1)
   python3-venv (3.9.0-4 => 3.9.1-1)
15 upgraded, 0 newly installed, 0 to remove and 222 not upgraded.


  songbird

From rosuav at gmail.com  Sun Dec 27 11:04:02 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 28 Dec 2020 03:04:02 +1100
Subject: Debian testing and virtual environment error message
In-Reply-To: <manmbh-uk5.ln1@anthive.com>
References: <iu0lbh-b73.ln1@anthive.com>
 <CAPTjJmreyiLJNj_V3W1QkTOwy2wYn4Z9f5MZZpsuPFQ084E0-Q@mail.gmail.com>
 <mailman.540.1609034326.7193.python-list@python.org>
 <manmbh-uk5.ln1@anthive.com>
Message-ID: <CAPTjJmq+6wfL_Euw+UD2sy85E8nX=vqO3ftPfTJjdWZnViuAfw@mail.gmail.com>

On Mon, Dec 28, 2020 at 2:56 AM songbird <songbird at anthive.com> wrote:
>
> Chris Angelico wrote:
>
>   ok, i got it to work.  i noticed that there was a 3.8
> version of distutils that was not upgraded to 3.9 so once
> i specifically pulled that in from the unstable Debian
> distribution then it upgraded and my creation of a new
> virtual environment would work without errors.
>

Ah, yep, that makes sense. I was a tad concerned about the mismatch of
versions, but honestly, I don't think I've ever installed Python from
testing or unstable (unless I'm running the entire distro on testing).
It's much much easier and safer to keep the system Python untouched,
and then build my own from source; my "python3" command, at the
moment, runs 3.10 pre-alpha.

ChrisA

From songbird at anthive.com  Sun Dec 27 12:11:13 2020
From: songbird at anthive.com (songbird)
Date: Sun, 27 Dec 2020 12:11:13 -0500
Subject: Debian testing and virtual environment error message
References: <iu0lbh-b73.ln1@anthive.com>
 <CAPTjJmreyiLJNj_V3W1QkTOwy2wYn4Z9f5MZZpsuPFQ084E0-Q@mail.gmail.com>
 <mailman.540.1609034326.7193.python-list@python.org>
 <manmbh-uk5.ln1@anthive.com>
 <CAPTjJmq+6wfL_Euw+UD2sy85E8nX=vqO3ftPfTJjdWZnViuAfw@mail.gmail.com>
 <mailman.541.1609085055.7193.python-list@python.org>
Message-ID: <hqrmbh-f87.ln1@anthive.com>

Chris Angelico wrote:
> On Mon, Dec 28, 2020 at 2:56 AM songbird <songbird at anthive.com> wrote:
...needed to pull a few more things from unstable...
> Ah, yep, that makes sense. I was a tad concerned about the mismatch of
> versions, but honestly, I don't think I've ever installed Python from
> testing or unstable (unless I'm running the entire distro on testing).
> It's much much easier and safer to keep the system Python untouched,
> and then build my own from source; my "python3" command, at the
> moment, runs 3.10 pre-alpha.

  it seems that if there is a dependency between these than it
should have be declared so they won't migrate to testing 
independently.  i'm not sure it is worth filing a bug about
since the transition is not completed yet anyways.

  i run testing on my day to day system because i do want to find
bugs before they make it to stable, especially for the things i
use every day.

  i'm not using the testing distribution for hard production tasks 
so if it breaks and i do need to get on-line i have a few other 
different bootable partitions or even a USB stick just in case.


  songbird

From christian at python.org  Sun Dec 27 16:45:20 2020
From: christian at python.org (Christian Heimes)
Date: Sun, 27 Dec 2020 22:45:20 +0100
Subject: Debian testing and virtual environment error message
In-Reply-To: <f9albh-l75.ln1@anthive.com>
References: <iu0lbh-b73.ln1@anthive.com> <f9albh-l75.ln1@anthive.com>
Message-ID: <rsav9m$116m$1@ciao.gmane.io>

On 27/12/2020 04.05, songbird wrote:
> songbird wrote:
> ...
>>   The package mentioned is installed:
>>
>>
>> =====
>>
>> $ dpkg -l | grep python3-venv
>> ii  python3-venv                         3.9.0-4                        amd64        pyvenv-3 binary for python3 (default python3 version)
>>
> 
>   here is something i missed including in my first post, but i don't
> know if this matters:
> 
> ii  python3.9-venv                       3.9.1-1                        amd64        Interactive high-level object-oriented language (pyvenv binary, version 3.9)

Don't worry, you are not the first person that ran into this issue.

Debian's packaging of Python has caused multiple issues. I have reported
some issues to downstream Debian/Ubuntu. You can find a list of all
known issues at
https://gist.github.com/tiran/2dec9e03c6f901814f6d1e8dad09528e

Christian


From sersadaka1 at outlook.com  Mon Dec 28 06:43:43 2020
From: sersadaka1 at outlook.com (Sadaka Technology)
Date: Mon, 28 Dec 2020 03:43:43 -0800 (PST)
Subject: kivy,,, assigning global variable
Message-ID: <c6aeceac-6ce0-4601-8212-d07aee953621n@googlegroups.com>

class main(..):

    def init.....:
        super.....
        button = Button(on_release=self.on_click)

    def on_click(self,screen,*args)
          self.clear_widgets()
          if screen == '2nd':
              float = 2nd()
          elif screen == '1st':
              float = 1st()
          self.add_widget(float)

class 2nd(...):
    string_text = StringProperty()
    def init.....:
        super.....
        Text = TextInput(text=self.string_text)
         button=Button(on_release=self.on_click)

    def on_click
          self.parent.on_click('1st')

class 1st(...):
     ............


#my only issue is in class 2nd() how can I change the value of the variable string_text, if I am clearing widgets and adding widget again in parent class ( main()), then string_text will again equal to empty ,   I tried to add string_text variable in main() but the same issue I am getting, how can I save the string_text in 2nd() if am removing it and adding it again ?

From Bischoop at vimart.net  Mon Dec 28 11:31:33 2020
From: Bischoop at vimart.net (Bischoop)
Date: Mon, 28 Dec 2020 16:31:33 -0000 (UTC)
Subject: Which method to check if string index is queal to character.
Message-ID: <slrnruk235.79g.Bischoop@vimart.net>

I'd like to check if there's "@" in a string and wondering if any method
is better/safer than others. I was told on one occasion that I should
use is than ==, so how would be on this example.

s = 'this at mail.is'

I want check if string is a valid email address.

code '''
import time

email = "ten at mail.tu"

start_time = time.time()
for i in range(len(email)):
  print('@' in email[i])

print ("My program took", time.time() - start_time, "to run")


print('----------')
start_time = time.time()
for i in range(len(email)):
    print(email[i] == '@')

print ("My program took", time.time() - start_time, "to run")
print('----------')
start_time = time.time()
if '@' in email:
    print('True')

print ("My program took", time.time() - start_time, "to run")

'''

From Marco.Sulla.Python at gmail.com  Mon Dec 28 12:46:19 2020
From: Marco.Sulla.Python at gmail.com (Marco Sulla)
Date: Mon, 28 Dec 2020 18:46:19 +0100
Subject: Which method to check if string index is queal to character.
In-Reply-To: <slrnruk235.79g.Bischoop@vimart.net>
References: <slrnruk235.79g.Bischoop@vimart.net>
Message-ID: <CABbU2U8XxzdQ_i=gS57ix0UmsvMdOPWmR8yLxdtieFDpY8kUNw@mail.gmail.com>

On Mon, 28 Dec 2020 at 17:37, Bischoop <Bischoop at vimart.net> wrote:
>
> I'd like to check if there's "@" in a string and wondering if any method
> is better/safer than others. I was told on one occasion that I should
> use is than ==, so how would be on this example.
>
> s = 'this at mail.is'

You could do simply

if "@" in s:

but probably what you really want is a regular expression.

From python at mrabarnett.plus.com  Mon Dec 28 13:32:00 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Mon, 28 Dec 2020 18:32:00 +0000
Subject: Which method to check if string index is queal to character.
In-Reply-To: <slrnruk235.79g.Bischoop@vimart.net>
References: <slrnruk235.79g.Bischoop@vimart.net>
Message-ID: <425e7ddc-615d-786e-f516-5c4848c86621@mrabarnett.plus.com>

On 2020-12-28 16:31, Bischoop wrote:
> I'd like to check if there's "@" in a string and wondering if any method
> is better/safer than others. I was told on one occasion that I should
> use is than ==, so how would be on this example.
> 
[snip]

The shortest and quickest way to check whether "@" is in my_string is:

     "@" in my_string

From Bischoop at vimart.net  Mon Dec 28 12:37:36 2020
From: Bischoop at vimart.net (Bischoop)
Date: Mon, 28 Dec 2020 17:37:36 -0000 (UTC)
Subject: Which method to check if string index is queal to character.
References: <slrnruk235.79g.Bischoop@vimart.net>
 <in-20201228180330@ram.dialup.fu-berlin.de>
Message-ID: <slrnruk5v0.79g.Bischoop@vimart.net>

On 2020-12-28, Stefan Ram <ram at zedat.fu-berlin.de> wrote:
>
>   "@" in s
>

That's what I thought.

>>I want check if string is a valid email address.
>
>   I suggest to first try and define "valid email address" in English.
>
>

A valid email address consists of an email prefix and an email domain,
both in acceptable formats. The prefix appears to the left of the @ symbol.
The domain appears to the right of the @ symbol.
For example, in the address example at mail.com, "example" is the email prefix,
and "mail.com" is the email domain.

--
Thanks

From tjreedy at udel.edu  Mon Dec 28 12:43:27 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 28 Dec 2020 12:43:27 -0500
Subject: Which method to check if string index is queal to character.
In-Reply-To: <slrnruk235.79g.Bischoop@vimart.net>
References: <slrnruk235.79g.Bischoop@vimart.net>
Message-ID: <rsd5g1$knu$1@ciao.gmane.io>

On 12/28/2020 11:31 AM, Bischoop wrote:
> I'd like to check if there's "@" in a string

Use the obvious "'@' in string".
  > and wondering if any method is better/safer than others.

Any special purpose method built into the language is likely to be 
fastest.  Safest?  What danger are you worried about?

> I was told on one occasion that I should
> use is than ==, so how would be on this example.

'is' is for detecting an exact match with a particular, singular object. 
  In particular, None, False, or True or user created objects meant for 
such use.

> s = 'this at mail.is'

> I want check if string is a valid email address.

There are two levels of validity: has the form of an address, which is 
much more complicated than the presence of an '@', and corresponds to a 
real email account.

> 
> code '''
> import time
> 
> email = "ten at mail.tu"
> 
> start_time = time.time()
> for i in range(len(email)):
>    print('@' in email[i])

This scans the entire string in a slow way, then indirectly performs '@' 
== char in a slow way.

> print ("My program took", time.time() - start_time, "to run")
> 
> 
> print('----------')
> start_time = time.time()
> for i in range(len(email)):
>      print(email[i] == '@')

Slightly better, does comparison directly.

for c in email:
    print(c == '@')

Faster and better way to scan.

for c in email:
    print(c == '@')
    break

Stops at first '@'.  '@' in email does the same, but should be slightly 
faster as it implements loop and break in the interpreter's 
implementation language.

> print ("My program took", time.time() - start_time, "to run")
> print('----------')
> start_time = time.time()
> if '@' in email:
>      print('True')
> 
> print ("My program took", time.time() - start_time, "to run")
> 
> '''
> 


-- 
Terry Jan Reedy


From rosuav at gmail.com  Mon Dec 28 14:23:31 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 29 Dec 2020 06:23:31 +1100
Subject: Which method to check if string index is queal to character.
In-Reply-To: <slrnruk5v0.79g.Bischoop@vimart.net>
References: <slrnruk235.79g.Bischoop@vimart.net>
 <in-20201228180330@ram.dialup.fu-berlin.de>
 <slrnruk5v0.79g.Bischoop@vimart.net>
Message-ID: <CAPTjJmpvijfDVz-CNJ1k3V+zgF14NbOHwgMBLNxo9sxgUQbzTg@mail.gmail.com>

On Tue, Dec 29, 2020 at 6:18 AM Bischoop <Bischoop at vimart.net> wrote:
>
> On 2020-12-28, Stefan Ram <ram at zedat.fu-berlin.de> wrote:
> >
> >   "@" in s
> >
>
> That's what I thought.
>
> >>I want check if string is a valid email address.
> >
> >   I suggest to first try and define "valid email address" in English.
> >
> >
>
> A valid email address consists of an email prefix and an email domain,
> both in acceptable formats. The prefix appears to the left of the @ symbol.
> The domain appears to the right of the @ symbol.
> For example, in the address example at mail.com, "example" is the email prefix,
> and "mail.com" is the email domain.
>

To see if it's a valid email address, send email to it and get the
person to verify receipt. Beyond that, all you can really check is
that it has an at sign in it (since a local address isn't usually
useful in contexts where you'd want to check).

So the check you are already looking at is sufficient.

ChrisA

From mats at wichmann.us  Mon Dec 28 15:08:22 2020
From: mats at wichmann.us (Mats Wichmann)
Date: Mon, 28 Dec 2020 13:08:22 -0700
Subject: Which method to check if string index is queal to character.
In-Reply-To: <CABbU2U8XxzdQ_i=gS57ix0UmsvMdOPWmR8yLxdtieFDpY8kUNw@mail.gmail.com>
References: <slrnruk235.79g.Bischoop@vimart.net>
 <CABbU2U8XxzdQ_i=gS57ix0UmsvMdOPWmR8yLxdtieFDpY8kUNw@mail.gmail.com>
Message-ID: <c0458de8-c38c-24be-9f63-cdb94f43e28a@wichmann.us>

On 12/28/20 10:46 AM, Marco Sulla wrote:
> On Mon, 28 Dec 2020 at 17:37, Bischoop <Bischoop at vimart.net> wrote:
>>
>> I'd like to check if there's "@" in a string and wondering if any method
>> is better/safer than others. I was told on one occasion that I should
>> use is than ==, so how would be on this example.
>>
>> s = 'this at mail.is'
> 
> You could do simply
> 
> if "@" in s:
> 
> but probably what you really want is a regular expression.
> 

Will add that Yes, you should always validate your inputs, but No, the 
presence of an @ sign in a text string is not sufficient to know it's a 
valid email address. Unfortunately validating that is hard.


From Richard at Damon-Family.org  Mon Dec 28 15:27:41 2020
From: Richard at Damon-Family.org (Richard Damon)
Date: Mon, 28 Dec 2020 15:27:41 -0500
Subject: Which method to check if string index is queal to character.
In-Reply-To: <c0458de8-c38c-24be-9f63-cdb94f43e28a@wichmann.us>
References: <slrnruk235.79g.Bischoop@vimart.net>
 <CABbU2U8XxzdQ_i=gS57ix0UmsvMdOPWmR8yLxdtieFDpY8kUNw@mail.gmail.com>
 <c0458de8-c38c-24be-9f63-cdb94f43e28a@wichmann.us>
Message-ID: <a897a258-37d4-a3eb-c556-6e75aa3bc4dc@Damon-Family.org>

On 12/28/20 3:08 PM, Mats Wichmann wrote:
> On 12/28/20 10:46 AM, Marco Sulla wrote:
>> On Mon, 28 Dec 2020 at 17:37, Bischoop <Bischoop at vimart.net> wrote:
>>>
>>> I'd like to check if there's "@" in a string and wondering if any
>>> method
>>> is better/safer than others. I was told on one occasion that I should
>>> use is than ==, so how would be on this example.
>>>
>>> s = 'this at mail.is'
>>
>> You could do simply
>>
>> if "@" in s:
>>
>> but probably what you really want is a regular expression.
>>
>
> Will add that Yes, you should always validate your inputs, but No, the
> presence of an @ sign in a text string is not sufficient to know it's
> a valid email address. Unfortunately validating that is hard.
>
Validating that it meets the SYNTAX of an email address isn't THAT hard,
but there are a number of edge cases to worry about.

Validating that it is a working email address (presumably after
verifying that it has a proper syntax) is much harder, and basically
requires trying to send to the address, and to really confirm that it is
good requires them to do something actively with a message you send
them. And then nothing says the address will continue to be valid.

-- 
Richard Damon


From torriem at gmail.com  Mon Dec 28 16:52:03 2020
From: torriem at gmail.com (Michael Torrie)
Date: Mon, 28 Dec 2020 14:52:03 -0700
Subject: Which method to check if string index is queal to character.
In-Reply-To: <slrnruk5v0.79g.Bischoop@vimart.net>
References: <slrnruk235.79g.Bischoop@vimart.net>
 <in-20201228180330@ram.dialup.fu-berlin.de>
 <slrnruk5v0.79g.Bischoop@vimart.net>
Message-ID: <ef1f129e-257f-d19a-d483-3d11ae3e2ffc@gmail.com>

On 12/28/20 10:37 AM, Bischoop wrote:
> A valid email address consists of an email prefix and an email domain,
> both in acceptable formats. The prefix appears to the left of the @ symbol.
> The domain appears to the right of the @ symbol.
> For example, in the address example at mail.com, "example" is the email prefix,
> and "mail.com" is the email domain.

Seems so simple, yet at least half the web sites I try to use get it
wrong.  There's an entire RFC on this topic.  Drives me crazy when a web
site insists that myaddress+suffix at domain.com is not a valid address.
It certainly is!

From torriem at gmail.com  Mon Dec 28 16:55:59 2020
From: torriem at gmail.com (Michael Torrie)
Date: Mon, 28 Dec 2020 14:55:59 -0700
Subject: Which method to check if string index is queal to character.
In-Reply-To: <CABbU2U8XxzdQ_i=gS57ix0UmsvMdOPWmR8yLxdtieFDpY8kUNw@mail.gmail.com>
References: <slrnruk235.79g.Bischoop@vimart.net>
 <CABbU2U8XxzdQ_i=gS57ix0UmsvMdOPWmR8yLxdtieFDpY8kUNw@mail.gmail.com>
Message-ID: <87a6a88f-398b-34ed-b614-766381cb720a@gmail.com>

On 12/28/20 10:46 AM, Marco Sulla wrote:
> On Mon, 28 Dec 2020 at 17:37, Bischoop <Bischoop at vimart.net> wrote:
>>
>> I'd like to check if there's "@" in a string and wondering if any method
>> is better/safer than others. I was told on one occasion that I should
>> use is than ==, so how would be on this example.
>>
>> s = 'this at mail.is'
> 
> You could do simply
> 
> if "@" in s:
> 
> but probably what you really want is a regular expression.

https://haacked.com/archive/2007/08/21/i-knew-how-to-validate-an-email-address-until-i.aspx/


From PythonList at DancesWithMice.info  Mon Dec 28 16:56:01 2020
From: PythonList at DancesWithMice.info (dn)
Date: Tue, 29 Dec 2020 10:56:01 +1300
Subject: Which method to check if string index is queal to character.
In-Reply-To: <a897a258-37d4-a3eb-c556-6e75aa3bc4dc@Damon-Family.org>
References: <slrnruk235.79g.Bischoop@vimart.net>
 <CABbU2U8XxzdQ_i=gS57ix0UmsvMdOPWmR8yLxdtieFDpY8kUNw@mail.gmail.com>
 <c0458de8-c38c-24be-9f63-cdb94f43e28a@wichmann.us>
 <a897a258-37d4-a3eb-c556-6e75aa3bc4dc@Damon-Family.org>
Message-ID: <ee3386b6-67a8-8f84-27a2-b0d8c4b5db44@DancesWithMice.info>

On 29/12/2020 09:27, Richard Damon wrote:
> On 12/28/20 3:08 PM, Mats Wichmann wrote:
>> On 12/28/20 10:46 AM, Marco Sulla wrote:
>>> On Mon, 28 Dec 2020 at 17:37, Bischoop <Bischoop at vimart.net> wrote:
...

>>> but probably what you really want is a regular expression.

<shudders>

because...


>> Will add that Yes, you should always validate your inputs, but No, the
>> presence of an @ sign in a text string is not sufficient to know it's
>> a valid email address. Unfortunately validating that is hard.


> Validating that it meets the SYNTAX of an email address isn't THAT hard,
> but there are a number of edge cases to worry about.
> 
> Validating that it is a working email address (presumably after
> verifying that it has a proper syntax) is much harder, and basically
> requires trying to send to the address, and to really confirm that it is
> good requires them to do something actively with a message you send
> them. And then nothing says the address will continue to be valid.


(am assuming the in/is question has been answered)


Looking at my email server log, I see messages addressed to 
"fd0d8f761aab at danceswithmice.info" - which have been rejected.

That spurious-address features an "@". It is a perfectly-formed email 
address. The domain-name is correct - and can be quickly verified as 
in-existence.

However the account-name is a total fabrication. (is someone trying to 
put a 'hex' on me?)


Accordingly, the advice that the only way to check if an email address 
is 'correct', is to see if it is accepted by the receiving-server. 
However, you can't (shouldn't be able to!) pierce that veil, to be able 
to prove/see for yourself!

That is why many subscription-systems send an initial email message and 
ask the receiver to confirm receipt by 'clicking on the link provided'!


Per previous RegEx discussions 'here': there are plenty of 
examples/attempts floating around the Internet. Absolutely none of which 
comes with a guarantee!

To quote the famous con-man/men/women: if you believe any such stories, 
come and see me about buying into the Brooklyn Bridge/some agricultural 
(marsh) land/the next best thing...

For many years, many of the RegEx-s circulating were so precise that 
they only recognised the original TLDs such as .com and .org. For years 
after .info was introduced, sites would tell me that my email address 
was 'illegal'. Leaving me to ask: do I really exist?, am I but part of 
some imaginary universe? (no comments about my Hobbit-feet, please!)


After such disparagement it is worth remembering that there are checks 
and there are checks! It depends upon the purpose of the check, or the 
level-of-detail/accuracy desired!

When accepting user-data it *is* worth (even "necessary") performing a 
'sanity-check'. Per @Chris, if the user doesn't enter two 'words' 
separated by an @-sign, and the second 'word' doesn't include at least 
one dot/period/stop, then it seems quite probable that our user has made 
a typo! This is why some sites require an email address to be entered 
twice. (but copy-paste anyone?)


Going much further than a typo-reducing/sanity-check is, per @Richard, 
considerably harder - and ultimately cannot guarantee an address. Thus, 
indulges in a sub-field of cyber-alchemy!
-- 
Regards =dn

From cs at cskk.id.au  Mon Dec 28 17:02:12 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Tue, 29 Dec 2020 09:02:12 +1100
Subject: Which method to check if string index is queal to character.
In-Reply-To: <c0458de8-c38c-24be-9f63-cdb94f43e28a@wichmann.us>
References: <c0458de8-c38c-24be-9f63-cdb94f43e28a@wichmann.us>
Message-ID: <X+pV5JJpnyn8pgST@cskk.homeip.net>

On 28Dec2020 13:08, Mats Wichmann <mats at wichmann.us> wrote:
>On 12/28/20 10:46 AM, Marco Sulla wrote:
>>On Mon, 28 Dec 2020 at 17:37, Bischoop <Bischoop at vimart.net> wrote:
>>>I'd like to check if there's "@" in a string and wondering if any 
>>>method is better/safer than others.

Others have pointed out: '@' in s

>Will add that Yes, you should always validate your inputs, but No, the 
>presence of an @ sign in a text string is not sufficient to know it's a 
>valid email address. Unfortunately validating that is hard.

Validating that it is a functional email address is hard, involves 
delivering email and then finding out if it was delivered.

A proper syntax check requires parsing an RFC5322 address grammar:

    https://tools.ietf.org/rfcmarkup/5322#section-3.4

Fortunately, Python ships with one of those in the email.utils module.

The parseaddr() function will parse a single address, and getaddresses() 
will parse a list of addresses such as might be in a To: header line.

They work well - I've been filing my email based on these for years - 
MANY thousands of messages.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From rosuav at gmail.com  Mon Dec 28 17:05:43 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 29 Dec 2020 09:05:43 +1100
Subject: Which method to check if string index is queal to character.
In-Reply-To: <ee3386b6-67a8-8f84-27a2-b0d8c4b5db44@DancesWithMice.info>
References: <slrnruk235.79g.Bischoop@vimart.net>
 <CABbU2U8XxzdQ_i=gS57ix0UmsvMdOPWmR8yLxdtieFDpY8kUNw@mail.gmail.com>
 <c0458de8-c38c-24be-9f63-cdb94f43e28a@wichmann.us>
 <a897a258-37d4-a3eb-c556-6e75aa3bc4dc@Damon-Family.org>
 <ee3386b6-67a8-8f84-27a2-b0d8c4b5db44@DancesWithMice.info>
Message-ID: <CAPTjJmoAg5qcEv6DeMO4_S+kHjYsKQfK8LBvQkg6+UUp7fV1DQ@mail.gmail.com>

On Tue, Dec 29, 2020 at 8:57 AM dn via Python-list
<python-list at python.org> wrote:
> After such disparagement it is worth remembering that there are checks
> and there are checks! It depends upon the purpose of the check, or the
> level-of-detail/accuracy desired!
>
> When accepting user-data it *is* worth (even "necessary") performing a
> 'sanity-check'. Per @Chris, if the user doesn't enter two 'words'
> separated by an @-sign, and the second 'word' doesn't include at least
> one dot/period/stop, then it seems quite probable that our user has made
> a typo! This is why some sites require an email address to be entered
> twice. (but copy-paste anyone?)

I wouldn't even ask for a dot in the second half, actually. Yes, it's
uncommon to have no dot, but it's fully legal, and not worth wrestling
with. Considering the vast number of typos that *wouldn't* trip a
filter, and the relatively small number that would, it's generally not
worth putting too much validation in.

Checking for the presence of "@" is a good way to check that it's an
email address and not, say, the URL of someone's webmail service, but
other than that, there's really not a lot that's worth checking.

OTOH, if you're trying to recognize email addresses in plain text
(say, in chat messages) so that you can autolink them, that's
completely different. Same with URLs (eg https://example.com/foo) -
you, as a human, can see that the URL should have ended at the "/foo",
but technically "/foo)" is perfectly legal. So if you're validating,
"/foo)" should be permitted, but if you're detecting, it should stop
at "/foo".

ChrisA

From Richard at Damon-Family.org  Mon Dec 28 17:59:21 2020
From: Richard at Damon-Family.org (Richard Damon)
Date: Mon, 28 Dec 2020 17:59:21 -0500
Subject: Which method to check if string index is queal to character.
In-Reply-To: <ef1f129e-257f-d19a-d483-3d11ae3e2ffc@gmail.com>
References: <slrnruk235.79g.Bischoop@vimart.net>
 <in-20201228180330@ram.dialup.fu-berlin.de>
 <slrnruk5v0.79g.Bischoop@vimart.net>
 <ef1f129e-257f-d19a-d483-3d11ae3e2ffc@gmail.com>
Message-ID: <f243edf5-318c-d53b-62fe-4350ebfbac6c@Damon-Family.org>

On 12/28/20 4:52 PM, Michael Torrie wrote:
> On 12/28/20 10:37 AM, Bischoop wrote:
>> A valid email address consists of an email prefix and an email domain,
>> both in acceptable formats. The prefix appears to the left of the @ symbol.
>> The domain appears to the right of the @ symbol.
>> For example, in the address example at mail.com, "example" is the email prefix,
>> and "mail.com" is the email domain.
> Seems so simple, yet at least half the web sites I try to use get it
> wrong.  There's an entire RFC on this topic.  Drives me crazy when a web
> site insists that myaddress+suffix at domain.com is not a valid address.
> It certainly is!

Yes, it really is fairly straight forward to do it right, but it does
have details that need to be checked carefully (It is significantly
harder if the email address can also contain comments or display names,
but just a base email address isn't that hard).

Many people do still get it wrong.

-- 
Richard Damon


From grant.b.edwards at gmail.com  Mon Dec 28 16:49:03 2020
From: grant.b.edwards at gmail.com (Grant Edwards)
Date: Mon, 28 Dec 2020 21:49:03 -0000 (UTC)
Subject: Which method to check if string index is queal to character.
References: <slrnruk235.79g.Bischoop@vimart.net>
 <in-20201228180330@ram.dialup.fu-berlin.de>
 <slrnruk5v0.79g.Bischoop@vimart.net>
Message-ID: <rsdjsf$16mg$1@ciao.gmane.io>

On 2020-12-28, Bischoop <Bischoop at vimart.net> wrote:
> On 2020-12-28, Stefan Ram <ram at zedat.fu-berlin.de> wrote:
>>
>>   "@" in s
>>
>
> That's what I thought.
>
>>>I want check if string is a valid email address.
>>
>>   I suggest to first try and define "valid email address" in English.
>
> A valid email address consists of an email prefix and an email domain,
> both in acceptable formats.

Well, that's assuming that bang routing/addresses aren't allowed. :)

--
Grant


From torriem at gmail.com  Mon Dec 28 16:54:14 2020
From: torriem at gmail.com (Michael Torrie)
Date: Mon, 28 Dec 2020 14:54:14 -0700
Subject: Which method to check if string index is queal to character.
In-Reply-To: <a897a258-37d4-a3eb-c556-6e75aa3bc4dc@Damon-Family.org>
References: <slrnruk235.79g.Bischoop@vimart.net>
 <CABbU2U8XxzdQ_i=gS57ix0UmsvMdOPWmR8yLxdtieFDpY8kUNw@mail.gmail.com>
 <c0458de8-c38c-24be-9f63-cdb94f43e28a@wichmann.us>
 <a897a258-37d4-a3eb-c556-6e75aa3bc4dc@Damon-Family.org>
Message-ID: <3f2d0d98-e638-fee5-a957-606dae023b05@gmail.com>

On 12/28/20 1:27 PM, Richard Damon wrote:
> Validating that it meets the SYNTAX of an email address isn't THAT hard,
> but there are a number of edge cases to worry about.

Yes one would think that, but in my experience half of all web sites get
it wrong, insisting that my perfectly valid and RFC-compliant email
address is not a proper email address.

From avigross at verizon.net  Mon Dec 28 18:01:03 2020
From: avigross at verizon.net (Avi Gross)
Date: Mon, 28 Dec 2020 18:01:03 -0500
Subject: Which method to check if string index is queal to character.
In-Reply-To: <CAPTjJmpvijfDVz-CNJ1k3V+zgF14NbOHwgMBLNxo9sxgUQbzTg@mail.gmail.com>
References: <slrnruk235.79g.Bischoop@vimart.net>
 <in-20201228180330@ram.dialup.fu-berlin.de>
 <slrnruk5v0.79g.Bischoop@vimart.net>
 <CAPTjJmpvijfDVz-CNJ1k3V+zgF14NbOHwgMBLNxo9sxgUQbzTg@mail.gmail.com>
Message-ID: <045e01d6dd6d$517f4f80$f47dee80$@verizon.net>

This may be a nit, but can we agree all valid email addresses as used today
have more than an @ symbol?

I see it as requiring at least one character before the @ that come from a
list of allowed characters (perhaps not ASCII) but does not include the
symbol @ again. It is normally followed by some minimal number of characters
and maybe  a period and one of the currently valid domains like .com or .it
but the latter gets tricky as it can look like user at abd.def.att.com or other
long variations where only the final component must be testable in the
program.

The lack of an at-sign suggests it is not an email address. The lack of
anything before or after also seems to disqualify it. You may be able to add
more conditions but as noted, having more than one at-sign may also
disqualify it.

I am sure someone has some complex regular expressions that they think
matches only potentially valid strings but, of course, as noted by Chris, to
really validate that an address works might require sending something and
validating a human replied and that can be quite  task.

-----Original Message-----
From: Python-list <python-list-bounces+avigross=verizon.net at python.org> On
Behalf Of Chris Angelico
Sent: Monday, December 28, 2020 2:24 PM
To: Python <python-list at python.org>
Subject: Re: Which method to check if string index is queal to character.

On Tue, Dec 29, 2020 at 6:18 AM Bischoop <Bischoop at vimart.net> wrote:
>
> On 2020-12-28, Stefan Ram <ram at zedat.fu-berlin.de> wrote:
> >
> >   "@" in s
> >
>
> That's what I thought.
>
> >>I want check if string is a valid email address.
> >
> >   I suggest to first try and define "valid email address" in English.
> >
> >
>
> A valid email address consists of an email prefix and an email domain, 
> both in acceptable formats. The prefix appears to the left of the @
symbol.
> The domain appears to the right of the @ symbol.
> For example, in the address example at mail.com, "example" is the email 
> prefix, and "mail.com" is the email domain.
>

To see if it's a valid email address, send email to it and get the person to
verify receipt. Beyond that, all you can really check is that it has an at
sign in it (since a local address isn't usually useful in contexts where
you'd want to check).

So the check you are already looking at is sufficient.

ChrisA
--
https://mail.python.org/mailman/listinfo/python-list


From rosuav at gmail.com  Mon Dec 28 20:02:04 2020
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 29 Dec 2020 12:02:04 +1100
Subject: Which method to check if string index is queal to character.
In-Reply-To: <045e01d6dd6d$517f4f80$f47dee80$@verizon.net>
References: <slrnruk235.79g.Bischoop@vimart.net>
 <in-20201228180330@ram.dialup.fu-berlin.de>
 <slrnruk5v0.79g.Bischoop@vimart.net>
 <CAPTjJmpvijfDVz-CNJ1k3V+zgF14NbOHwgMBLNxo9sxgUQbzTg@mail.gmail.com>
 <045e01d6dd6d$517f4f80$f47dee80$@verizon.net>
Message-ID: <CAPTjJmq_xDYfAaNP_+19mN49TbRowNeDWpq5s2M6m5BX_-4VfA@mail.gmail.com>

On Tue, Dec 29, 2020 at 10:08 AM Avi Gross via Python-list
<python-list at python.org> wrote:
>
> This may be a nit, but can we agree all valid email addresses as used today
> have more than an @ symbol?
>
> I see it as requiring at least one character before the @ that come from a
> list of allowed characters (perhaps not ASCII) but does not include the
> symbol @ again. It is normally followed by some minimal number of characters
> and maybe  a period and one of the currently valid domains like .com or .it
> but the latter gets tricky as it can look like user at abd.def.att.com or other
> long variations where only the final component must be testable in the
> program.

There can be an @ in the first part of the address, and the domain may
well not have a dot.

> The lack of an at-sign suggests it is not an email address. The lack of
> anything before or after also seems to disqualify it. You may be able to add
> more conditions but as noted, having more than one at-sign may also
> disqualify it.

Lack of an at sign means it's a local address that can't be routed
over the internet, and in many contexts, it's reasonable to exclude
those. But two isn't illegal.

> I am sure someone has some complex regular expressions that they think
> matches only potentially valid strings but, of course, as noted by Chris, to
> really validate that an address works might require sending something and
> validating a human replied and that can be quite  task.
>

Yes, many such regexes exist, and they are *all wrong*. Without
exception. I don't think it's actually possible for a regex to
perfectly match all (syntactically) valid email addresses and nothing
else.

ChrisA

From avigross at verizon.net  Mon Dec 28 20:37:42 2020
From: avigross at verizon.net (Avi Gross)
Date: Mon, 28 Dec 2020 20:37:42 -0500
Subject: Which method to check if string index is queal to character.
In-Reply-To: <CAPTjJmq_xDYfAaNP_+19mN49TbRowNeDWpq5s2M6m5BX_-4VfA@mail.gmail.com>
References: <slrnruk235.79g.Bischoop@vimart.net>
 <in-20201228180330@ram.dialup.fu-berlin.de>
 <slrnruk5v0.79g.Bischoop@vimart.net>
 <CAPTjJmpvijfDVz-CNJ1k3V+zgF14NbOHwgMBLNxo9sxgUQbzTg@mail.gmail.com>
 <045e01d6dd6d$517f4f80$f47dee80$@verizon.net>
 <CAPTjJmq_xDYfAaNP_+19mN49TbRowNeDWpq5s2M6m5BX_-4VfA@mail.gmail.com>
Message-ID: <063501d6dd83$33b48090$9b1d81b0$@verizon.net>

Thanks, Chris,

I am not actually up-to-date on such messaging issues but not shocked at
what you wrote. Years ago I recall most messages going out of my workplace
looked like machine!machine2!ihnp4!more!evenmore!user with no @ in sight and
as you mention, you may want to send to a domain and have it send to a
subdomain so a multiple @ may make sense and so on. I note we have some
places like groups.io that disguise the @ in your original email address so
you can still see who it is from, even though it is in some sense from them
but to actually use the email address in your own mailer, you need to
substitute it back in. 

I think we all agree that unless there is further standardization, an email
address can easily be rejected that is otherwise usable in some context and
that one in proper format (by some definition) will fail in that context.

The original question actually focused more narrowly on a good way to find
if a character existed in a string for which regular expressions need not
apply and most email addresses re short enough that techniques to speed up
the search may not be useful unless all the program does is search millions
of email addresses for the presence.

Dropping out, ...

-----Original Message-----
From: Python-list <python-list-bounces+avigross=verizon.net at python.org> On
Behalf Of Chris Angelico
Sent: Monday, December 28, 2020 8:02 PM
To: Python <python-list at python.org>
Subject: Re: Which method to check if string index is queal to character.

On Tue, Dec 29, 2020 at 10:08 AM Avi Gross via Python-list
<python-list at python.org> wrote:
>
> This may be a nit, but can we agree all valid email addresses as used 
> today have more than an @ symbol?
>
> I see it as requiring at least one character before the @ that come 
> from a list of allowed characters (perhaps not ASCII) but does not 
> include the symbol @ again. It is normally followed by some minimal 
> number of characters and maybe  a period and one of the currently 
> valid domains like .com or .it but the latter gets tricky as it can 
> look like user at abd.def.att.com or other long variations where only the 
> final component must be testable in the program.

There can be an @ in the first part of the address, and the domain may well
not have a dot.

> The lack of an at-sign suggests it is not an email address. The lack 
> of anything before or after also seems to disqualify it. You may be 
> able to add more conditions but as noted, having more than one at-sign 
> may also disqualify it.

Lack of an at sign means it's a local address that can't be routed over the
internet, and in many contexts, it's reasonable to exclude those. But two
isn't illegal.

> I am sure someone has some complex regular expressions that they think 
> matches only potentially valid strings but, of course, as noted by 
> Chris, to really validate that an address works might require sending 
> something and validating a human replied and that can be quite  task.
>

Yes, many such regexes exist, and they are *all wrong*. Without exception. I
don't think it's actually possible for a regex to perfectly match all
(syntactically) valid email addresses and nothing else.

ChrisA
--
https://mail.python.org/mailman/listinfo/python-list


From Bischoop at vimart.net  Mon Dec 28 20:48:16 2020
From: Bischoop at vimart.net (Bischoop)
Date: Tue, 29 Dec 2020 01:48:16 -0000 (UTC)
Subject: Which method to check if string index is queal to character.
References: <slrnruk235.79g.Bischoop@vimart.net>
 <CABbU2U8XxzdQ_i=gS57ix0UmsvMdOPWmR8yLxdtieFDpY8kUNw@mail.gmail.com>
 <c0458de8-c38c-24be-9f63-cdb94f43e28a@wichmann.us>
 <mailman.547.1609186156.7193.python-list@python.org>
Message-ID: <slrnrul2n0.h12.Bischoop@vimart.net>

On 2020-12-28, Mats Wichmann <mats at wichmann.us> wrote:
> On 12/28/20 10:46 AM, Marco Sulla wrote:
>> On Mon, 28 Dec 2020 at 17:37, Bischoop <Bischoop at vimart.net> wrote:
>>>
>>> I'd like to check if there's "@" in a string and wondering if any method
>>> is better/safer than others. I was told on one occasion that I should
>>> use is than ==, so how would be on this example.
>>>
>>> s = 'this at mail.is'
>> 
>> You could do simply
>> 
>> if "@" in s:
>> 
>> but probably what you really want is a regular expression.
>> 
>
> Will add that Yes, you should always validate your inputs, but No, the 
> presence of an @ sign in a text string is not sufficient to know it's a 
> valid email address. Unfortunately validating that is hard.
>

Nah, by saying if is valid I meant exeactly if there's "@", I could add
yet if endswith() but at this point @ is enough. 
Yes the only possible way for full validation would be just sending
email and waiting for reply.

From Richard at Damon-Family.org  Mon Dec 28 21:01:42 2020
From: Richard at Damon-Family.org (Richard Damon)
Date: Mon, 28 Dec 2020 21:01:42 -0500
Subject: Which method to check if string index is queal to character.
In-Reply-To: <CAPTjJmq_xDYfAaNP_+19mN49TbRowNeDWpq5s2M6m5BX_-4VfA@mail.gmail.com>
References: <slrnruk235.79g.Bischoop@vimart.net>
 <in-20201228180330@ram.dialup.fu-berlin.de>
 <slrnruk5v0.79g.Bischoop@vimart.net>
 <CAPTjJmpvijfDVz-CNJ1k3V+zgF14NbOHwgMBLNxo9sxgUQbzTg@mail.gmail.com>
 <045e01d6dd6d$517f4f80$f47dee80$@verizon.net>
 <CAPTjJmq_xDYfAaNP_+19mN49TbRowNeDWpq5s2M6m5BX_-4VfA@mail.gmail.com>
Message-ID: <1eb5b91f-e713-374f-4349-b99dd1b29d82@Damon-Family.org>

On 12/28/20 8:02 PM, Chris Angelico wrote:
>
> Yes, many such regexes exist, and they are *all wrong*. Without
> exception. I don't think it's actually possible for a regex to
> perfectly match all (syntactically) valid email addresses and nothing
> else.
>
> ChrisA

Since Email addresses are allowed to have (comments) in them, and
comments are allowed to nest, I think it takes something stronger than a
regex to fully process them, but takes something that can handle a
recursive grammar.

I think that is the only thing that absolutely prevents using a regex
(but not sure about it) but some of the rules will make things messy and
need to use alternation and repetition.

The one other thing that might block a regex is I think there is an
upper limits to how long the address (or its parts) are allowed to be,
and testing that at the same time as the other patterns is probably
beyond what a regex could handle.

-- 
Richard Damon


From Bischoop at vimart.net  Mon Dec 28 20:51:29 2020
From: Bischoop at vimart.net (Bischoop)
Date: Tue, 29 Dec 2020 01:51:29 -0000 (UTC)
Subject: Which method to check if string index is queal to character.
References: <slrnruk235.79g.Bischoop@vimart.net>
 <CABbU2U8XxzdQ_i=gS57ix0UmsvMdOPWmR8yLxdtieFDpY8kUNw@mail.gmail.com>
 <87a6a88f-398b-34ed-b614-766381cb720a@gmail.com>
 <mailman.550.1609192564.7193.python-list@python.org>
Message-ID: <slrnrul2t1.h12.Bischoop@vimart.net>

On 2020-12-28, Michael Torrie <torriem at gmail.com> wrote:
> On 12/28/20 10:46 AM, Marco Sulla wrote:
>> On Mon, 28 Dec 2020 at 17:37, Bischoop <Bischoop at vimart.net> wrote:
>>>
>>> I'd like to check if there's "@" in a string and wondering if any method
>>> is better/safer than others. I was told on one occasion that I should
>>> use is than ==, so how would be on this example.
>>>
>>> s = 'this at mail.is'
>> 
>> You could do simply
>> 
>> if "@" in s:
>> 
>> but probably what you really want is a regular expression.
>
> https://haacked.com/archive/2007/08/21/i-knew-how-to-validate-an-email-address-until-i.aspx/
>

Interested article.

--
Thanks

From jcasale at activenetwerx.com  Mon Dec 28 21:56:16 2020
From: jcasale at activenetwerx.com (Joseph L. Casale)
Date: Tue, 29 Dec 2020 02:56:16 +0000
Subject: asyncio cancellation pattern
Message-ID: <6e17b6d6d5e7482bbd84de8ecec2c31b@activenetwerx.com>

I've started writing some asyncio code in lieu of using threads and
managing concurrency and primitives manually.

Having spent a lot of time using c#'s async implementation, I am struggling
to see an elegant pattern for implementing cancellation. With the necessity
for the loop (that of which I understand) and the disconnect between
context and tasks, how does one act on a failure within a task and invoke
cancellation upwards.

Collecting all tasks and cancelling everything is not appropriate, they may
not necessarily all be part of the graph that needs cancelling.

In c#, we have several patterns available using a cancellation token source
and either passing the token (event only) into the task, or the token source
into the task execution context for signaling during a failure.

Does an easier way then manually creating tasks from coroutines and
tracking them explicitly exist?

Thanks,
jlc

From nospam at please.ty  Tue Dec 29 04:53:01 2020
From: nospam at please.ty (jak)
Date: Tue, 29 Dec 2020 10:53:01 +0100
Subject: Which method to check if string index is queal to character.
References: <slrnruk235.79g.Bischoop@vimart.net>
 <CABbU2U8XxzdQ_i=gS57ix0UmsvMdOPWmR8yLxdtieFDpY8kUNw@mail.gmail.com>
 <c0458de8-c38c-24be-9f63-cdb94f43e28a@wichmann.us>
 <mailman.547.1609186156.7193.python-list@python.org>
 <slrnrul2n0.h12.Bischoop@vimart.net>
Message-ID: <rseu9r$14c7$1@gioia.aioe.org>

Il 29/12/2020 02:48, Bischoop ha scritto:
> On 2020-12-28, Mats Wichmann <mats at wichmann.us> wrote:
>> On 12/28/20 10:46 AM, Marco Sulla wrote:
>>> On Mon, 28 Dec 2020 at 17:37, Bischoop <Bischoop at vimart.net> wrote:
>>>>
>>>> I'd like to check if there's "@" in a string and wondering if any method
>>>> is better/safer than others. I was told on one occasion that I should
>>>> use is than ==, so how would be on this example.
>>>>
>>>> s = 'this at mail.is'
>>>
>>> You could do simply
>>>
>>> if "@" in s:
>>>
>>> but probably what you really want is a regular expression.
>>>
>>
>> Will add that Yes, you should always validate your inputs, but No, the
>> presence of an @ sign in a text string is not sufficient to know it's a
>> valid email address. Unfortunately validating that is hard.
>>
> 
> Nah, by saying if is valid I meant exeactly if there's "@", I could add
> yet if endswith() but at this point @ is enough.
> Yes the only possible way for full validation would be just sending
> email and waiting for reply.
> 

you could try this way:

# -----------
from dns import resolver as dns

emails=['john.doe at fakeserver.bah',
         'john.doe at gmail.com']

for ue in emails:
     try:
         mxl = dns.resolve(ue.split('@')[1], 'MX')
     except:
         print(f'{ue}: bad mail server')
     else:
         if len(mxl) > 0:
             print(f'{ue}: valid mail server')
# -----------

... so, having verified the sever, you should only worry about the name.

From sapna.intell at gmail.com  Tue Dec 29 05:52:15 2020
From: sapna.intell at gmail.com (Priya Singh)
Date: Tue, 29 Dec 2020 02:52:15 -0800 (PST)
Subject: 2 sample chi-square test
Message-ID: <4601f428-a77a-4105-8f14-0aea561e0f4fn@googlegroups.com>

Hi all,

I have two spectra with wavelength, flux, and error on flux. I want to find out the variability of these two spectra based on the 2 sample Chi-square test. 
I am using following code:

def compute_chi2_var(file1,file2,zemi,vmin,vmax):
    w1,f1,e1,c1,vel1 = get_spec_vel(dir_data+file1,zemi)
    id1 = np.where(np.logical_and(vel1 >= vmin, vel1 < vmax))[0]   
    w2,f2,e2,c2,vel2 = get_spec_vel(dir_data+file2,zemi)
    id2 = np.where(np.logical_and(vel2 >= vmin, vel2 < vmax))[0]
    f_int = interp1d(w1[id1], f1[id1]/c1[id1], kind='cubic')
    e_int = interp1d(w1[id1], e1[id1]/c1[id1], kind='cubic')  
    f_obs,e_obs  = f_int(w2[id2]), e_int(w2[id2]) 
    f_exp, e_exp = f2[id2]/c2[id2], e2[id2]/c2[id2]
    e_net = e_obs**2 + e_exp**2
    chi_square =  np.sum( (f_obs**2 -  f_exp**2)/e_net  )
    dof = len(f_obs) - 1
    pval = 1 - stats.chi2.cdf( chi_square, dof)
    print('%.10E' % pval)

NN = 320
compute_chi2_var(file7[NN],file14[NN],zemi[NN],vmin[NN],vmax[NN])

I am running this code on many files, and I want to grab those pair of spectra where, the p-value of chi-squa is less than 10^(-8),  for the change to be unlikely due to a random occurrence.
Is my code right concept-wise? Because the chi-squ value is coming out to be very large (positive and negative), such that my p-value is always between 1 and 0 which I know from other's results not correct.

Can anyone suggest me is the concept of 2-sample chi-squ applied by me is correct or not?

I thank you all in advance.
 

From nikhilclt87 at gmail.com  Tue Dec 29 08:38:53 2020
From: nikhilclt87 at gmail.com (nikhil k)
Date: Tue, 29 Dec 2020 05:38:53 -0800 (PST)
Subject: How to copy the entire outlook message content in python
Message-ID: <b7777609-dd0a-4533-943f-609861bd2ca1n@googlegroups.com>

Hello All,
I'm a beginner trying to achieve the below in my python script: Can anyone help me on this?  I'm stuck at step2.

1. Input: A locally saved outlook mail (*.msg) path
2. Go to the path and Copy the entire body of the mail 
3. Create a new mail and paste the contents into new mail 
4. send it manually

# ========================================================
# =======================   Script Start ======================
# ========================================================
import win32com.client as win32  

########### Functions
def getMailBody(msgFile):
    start_text = "<html>"
    end_text = "</html>"
    with open(msgFile) as f:
        data=f.read()
    return data[data.find(start_text):data.find(end_text)+len(end_text)]

def releaseMail(body, subject, recipient):
    outlook = win32.Dispatch('outlook.application')
    mail = outlook.CreateItem(0)
    mail.To = recipient
    mail.Subject = subject
    mail.HtmlBody = body
    mail.Display(True)

############### Main ################
msgFile = "C:\\RELM\\testMsg.msg"
mailTo = "mymail at myserver.com"
mailSubject = "Test message"
mailBody = getMailBody(msgFile)
releaseMail(mailBody, mailSubject, mailRecipient)
# ========================================================
# ======================== Script End =======================  
# ========================================================


Below is the error I'm getting.
==============================================
  File "C:\Python\Python38-32\lib\encodings\cp1252.py", line 23, in decode
    return codecs.charmap_decode(input,self.errors,decoding_table)[0]
UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 924: character maps to <undefined>



From cl at isbd.net  Tue Dec 29 09:03:00 2020
From: cl at isbd.net (Chris Green)
Date: Tue, 29 Dec 2020 14:03:00 +0000
Subject: How to uninstall python 2 package specifically?
Message-ID: <khprbh-9pa3.ln1@esprimo.zbmc.eu>

I have two (or maybe even three) versions of Click installed:-

/usr/local/lib/python2.7/dist-packages/click
/usr/local/lib/python3.7/dist-packages/click
/usr/lib/python3/dist-packages/click

I run [x]ubuntu.

How can I uninstall those extra versions of click (which have
presumably been installed by pip, how would I know?).

-- 
Chris Green
?

From cl at isbd.net  Tue Dec 29 09:48:39 2020
From: cl at isbd.net (Chris Green)
Date: Tue, 29 Dec 2020 14:48:39 +0000
Subject: Is there any way to check/de-cruft/update Python packages installed
 using pip?
Message-ID: <77srbh-fgf3.ln1@esprimo.zbmc.eu>

I seem to have quite a lot of old python packages installed over the
years using pip and would like, if I can. to clear some of them out.


Is there any way to tell if a python package was installed by me
directly using pip or was installed from the [x]ubuntu repositories?
'pip list' just tells me every python package that's installed and
this really isn't much help.


Can one uninstall older versions?  For example I seem to have
three versions of Click installed:-

    /usr/local/lib/python2.7/dist-packages/click
    /usr/local/lib/python3.7/dist-packages/click
    /usr/lib/python3/dist-packages/click

Presumably the ones in /usr/local have been pulled in as dependencies
when installing something else using pip, the /usr/lib one has been
installed from the Ubuntu repositories (again as a dependency). How
can I remove the ones in /usr/local?


If one updates a package using pip will it move it as appropriate from
(for example) /usr/local/lib/python3.7 to /usr/local/lib/python3.8?


Can pip (or some other tool) tell me what other python packages depend
on one I'm considering uninstalling?


If there are any tools/utilities one can install to check these things
out I'd love to know about them.

-- 
Chris Green
?

From cl at isbd.net  Tue Dec 29 10:10:01 2020
From: cl at isbd.net (Chris Green)
Date: Tue, 29 Dec 2020 15:10:01 +0000
Subject: Why do I have both /usr/lib/python3 and /usr/lib/python3.8?
Message-ID: <9ftrbh-97i3.ln1@esprimo.zbmc.eu>

Why are there both /usr/lib/python3 and /usr/lib/python3.8 on my
x[ubuntu] system?

/usr/lib/python3 has just the dist-packages directory in it,
/usr/lib/python3.8 has lots of individual python files in it as well
as quite a number of directories.  

There's also a /usr/lib/python3.9 directory even though Ubuntu hasn't
moved to python3.9 yet.


-- 
Chris Green
?

From pkpearson at nowhere.invalid  Tue Dec 29 11:47:45 2020
From: pkpearson at nowhere.invalid (Peter Pearson)
Date: 29 Dec 2020 16:47:45 GMT
Subject: 2 sample chi-square test
References: <4601f428-a77a-4105-8f14-0aea561e0f4fn@googlegroups.com>
Message-ID: <i514thF4fpjU1@mid.individual.net>

On Tue, 29 Dec 2020 02:52:15 -0800 (PST), Priya Singh wrote:
[snip]
> I have two spectra with wavelength, flux, and error on flux. I want to
> find out the variability of these two spectra based on the 2 sample
> Chi-square test.  I am using following code:
>
> def compute_chi2_var(file1,file2,zemi,vmin,vmax):
>     w1,f1,e1,c1,vel1 = get_spec_vel(dir_data+file1,zemi)
>     id1 = np.where(np.logical_and(vel1 >= vmin, vel1 < vmax))[0]   
>     w2,f2,e2,c2,vel2 = get_spec_vel(dir_data+file2,zemi)
>     id2 = np.where(np.logical_and(vel2 >= vmin, vel2 < vmax))[0]
>     f_int = interp1d(w1[id1], f1[id1]/c1[id1], kind='cubic')
>     e_int = interp1d(w1[id1], e1[id1]/c1[id1], kind='cubic')  
>     f_obs,e_obs  = f_int(w2[id2]), e_int(w2[id2]) 
>     f_exp, e_exp = f2[id2]/c2[id2], e2[id2]/c2[id2]
>     e_net = e_obs**2 + e_exp**2
>     chi_square =  np.sum( (f_obs**2 -  f_exp**2)/e_net  )
>     dof = len(f_obs) - 1
>     pval = 1 - stats.chi2.cdf( chi_square, dof)
>     print('%.10E' % pval)
>
> NN = 320
> compute_chi2_var(file7[NN],file14[NN],zemi[NN],vmin[NN],vmax[NN])
>
>
> I am running this code on many files, and I want to grab those pair of
> spectra where, the p-value of chi-squa is less than 10^(-8), for the
> change to be unlikely due to a random occurrence.
>
> Is my code right concept-wise? Because the chi-squ value is coming out
> to be very large (positive and negative), such that my p-value is
> always between 1 and 0 which I know from other's results not correct.
>
> Can anyone suggest me is the concept of 2-sample chi-squ applied by me
> is correct or not?

1. This is not really a Python question, is it?

2. Recommendation: test your chi-squared code on simpler sample data.

3. Observation: P-values *are* normally between 0 and 1.

4. Observation: chi-squared values are never negative.

5. Recommendation: Learn a little about the chi-squared distribution
   (but not on a Python newsgroup).  The chi-squared distribution with
   N degrees of freedom is the distribution expected for a quantity
   that is the sum of the squares of N normally distributed random
   variables with mean 0 and standard deviation 1.  If you expect
   f_obs to equal f_exp plus some normally distributed noise with
   mean 0 and standard deviation sigma, then (f_obs-f_exp)/sigma
   should be normally distributed with mean 0 and standard deviation 1.

6. Observation: (f_obs**2 -  f_exp**2)/e_net is probably not what
   you want, since it can be negative.  You probably want something
   like (f_obs-f_exp)**2/e_net.  But don't take my word for it.

Good luck.

-- 
To email me, substitute nowhere->runbox, invalid->com.

From pkpearson at nowhere.invalid  Tue Dec 29 12:07:06 2020
From: pkpearson at nowhere.invalid (Peter Pearson)
Date: 29 Dec 2020 17:07:06 GMT
Subject: How to copy the entire outlook message content in python
References: <b7777609-dd0a-4533-943f-609861bd2ca1n@googlegroups.com>
Message-ID: <i5161qF4fpjU2@mid.individual.net>

On Tue, 29 Dec 2020 05:38:53 -0800 (PST), nikhil k wrote:
...[snip]...
> import win32com.client as win32  
>
> ########### Functions
> def getMailBody(msgFile):
>     start_text = "<html>"
>     end_text = "</html>"
>     with open(msgFile) as f:
>         data=f.read()
>     return data[data.find(start_text):data.find(end_text)+len(end_text)]
...[snip]...
>
>
> Below is the error I'm getting.
>==============================================
>   File "C:\Python\Python38-32\lib\encodings\cp1252.py", line 23, in decode
>     return codecs.charmap_decode(input,self.errors,decoding_table)[0]
> UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 924: character maps to <undefined>

I'm not completely sure that it's the f.read() call that produces
the error, because you cut out the earlier lines of the error
message, but . . .

I think the problem is that the data in the file you're reading
do not represent a valid "encoding" of any character string,
using whatever encoding convention Python thinks you want to use.
Maybe Python is assuming you're using ASCII encoding; 0x81 is
certainly not a valid ASCII character.

I don't know how Outlook represents messages in its .msg files;
it's possible it packs ASCII text along with binary data.

Maybe you can find a Python package that reads .msg files.

Maybe you could read the file as a bytestring instead of as a
character string.


-- 
To email me, substitute nowhere->runbox, invalid->com.

From rshepard at appl-ecosys.com  Tue Dec 29 13:11:32 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Tue, 29 Dec 2020 10:11:32 -0800 (PST)
Subject: Learning why module will not load
Message-ID: <alpine.LNX.2.20.2012291007150.9439@salmo.appl-ecosys.com>

Running Slackware-14.2/x86_64 and python-3.9.1. Installed are
six-1.14.0-x86_64-1_SBo and python3-six-1.13.0-x86_64-1_SBo (I don't know if
the latter is required because six is supposed to be available for python2
and python3.)

However, python3 doesn't find either one:

$ python3
Python 3.9.1 (default, Dec 26 2020, 11:21:00) 
[GCC 5.5.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import six
Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'six'
>>> import python3_six
Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'python3_six'

How do I diagnose why neither module is found?

TIA,

Rich



From mats at wichmann.us  Tue Dec 29 13:12:53 2020
From: mats at wichmann.us (Mats Wichmann)
Date: Tue, 29 Dec 2020 11:12:53 -0700
Subject: Is there any way to check/de-cruft/update Python packages
 installed using pip?
In-Reply-To: <77srbh-fgf3.ln1@esprimo.zbmc.eu>
References: <77srbh-fgf3.ln1@esprimo.zbmc.eu>
Message-ID: <d70e6bd8-3dc5-aec2-e8ec-d821e8466f79@wichmann.us>

On 12/29/20 7:48 AM, Chris Green wrote:
> I seem to have quite a lot of old python packages installed over the
> years using pip and would like, if I can. to clear some of them out.
> 
> 
> Is there any way to tell if a python package was installed by me
> directly using pip or was installed from the [x]ubuntu repositories?
> 'pip list' just tells me every python package that's installed and
> this really isn't much help.
> 
> 
> Can one uninstall older versions?  For example I seem to have
> three versions of Click installed:-
> 
>      /usr/local/lib/python2.7/dist-packages/click
>      /usr/local/lib/python3.7/dist-packages/click
>      /usr/lib/python3/dist-packages/click
> 
> Presumably the ones in /usr/local have been pulled in as dependencies
> when installing something else using pip, the /usr/lib one has been
> installed from the Ubuntu repositories (again as a dependency). How
> can I remove the ones in /usr/local?
> 
> 
> If one updates a package using pip will it move it as appropriate from
> (for example) /usr/local/lib/python3.7 to /usr/local/lib/python3.8?
> 
> 
> Can pip (or some other tool) tell me what other python packages depend
> on one I'm considering uninstalling?
> 
> 
> If there are any tools/utilities one can install to check these things
> out I'd love to know about them.

There are some tools (on pypi naturally) for fiddling with installed 
packages, but for starters try these two:

python -m pip help list
python -m pip help show

show will list dependencies, among other bits of info.

For older versions, you to use the matching version of Python

python2.7 -m pip show click


From cl at isbd.net  Tue Dec 29 13:21:14 2020
From: cl at isbd.net (Chris Green)
Date: Tue, 29 Dec 2020 18:21:14 +0000
Subject: Is there any way to check/de-cruft/update Python packages
 installed using pip?
References: <77srbh-fgf3.ln1@esprimo.zbmc.eu>
 <d70e6bd8-3dc5-aec2-e8ec-d821e8466f79@wichmann.us>
 <mailman.565.1609265633.7193.python-list@python.org>
Message-ID: <ql8sbh-a6i.ln1@esprimo.zbmc.eu>

Mats Wichmann <mats at wichmann.us> wrote:
> On 12/29/20 7:48 AM, Chris Green wrote:
> > 
> > If there are any tools/utilities one can install to check these things
> > out I'd love to know about them.
> 
> There are some tools (on pypi naturally) for fiddling with installed 
> packages, but for starters try these two:
> 
> python -m pip help list
> python -m pip help show
> 
> show will list dependencies, among other bits of info.
> 
> For older versions, you to use the matching version of Python
> 
> python2.7 -m pip show click
> 
Ah, of course, run pip using the python version that matches what you
want to remove, obvious really! :-)   Thanks.

-- 
Chris Green
?

From tjreedy at udel.edu  Tue Dec 29 13:31:36 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 29 Dec 2020 13:31:36 -0500
Subject: Learning why module will not load
In-Reply-To: <alpine.LNX.2.20.2012291007150.9439@salmo.appl-ecosys.com>
References: <alpine.LNX.2.20.2012291007150.9439@salmo.appl-ecosys.com>
Message-ID: <rsfsm8$u4$1@ciao.gmane.io>

On 12/29/2020 1:11 PM, Rich Shepard wrote:
> Running Slackware-14.2/x86_64 and python-3.9.1. Installed are
> six-1.14.0-x86_64-1_SBo and python3-six-1.13.0-x86_64-1_SBo (I don't 
> know if
> the latter is required because six is supposed to be available for python2
> and python3.)

Packages have to be installed for a particular Python binary in order 
for that binary to import the package.

> However, python3 doesn't find either one:
> 
> $ python3
> Python 3.9.1 (default, Dec 26 2020, 11:21:00) [GCC 5.5.0] on linux
> Type "help", "copyright", "credits" or "license" for more information.
>>>> import six
> Traceback (most recent call last):
>  ? File "<stdin>", line 1, in <module>
> ModuleNotFoundError: No module named 'six'
>>>> import python3_six
> Traceback (most recent call last):
>  ? File "<stdin>", line 1, in <module>
> ModuleNotFoundError: No module named 'python3_six'
> 
> How do I diagnose why neither module is found?

Those packages apparently are not installed for that 3.9.1 binary.


-- 
Terry Jan Reedy



From funkyhat at gmail.com  Tue Dec 29 13:43:39 2020
From: funkyhat at gmail.com (Matt Wheeler)
Date: Tue, 29 Dec 2020 18:43:39 +0000
Subject: Is there any way to check/de-cruft/update Python packages
 installed using pip?
In-Reply-To: <77srbh-fgf3.ln1@esprimo.zbmc.eu>
References: <77srbh-fgf3.ln1@esprimo.zbmc.eu>
Message-ID: <fffa2c6f-ed31-4734-a676-a889e3ced0a6@Spark>

On 29 Dec 2020, 14:48 +0000, Chris Green <cl at isbd.net>, wrote:
> I seem to have quite a lot of old python packages installed over the
> years using pip and would like, if I can. to clear some of them out.
>
>
> Is there any way to tell if a python package was installed by me
> directly using pip or was installed from the [x]ubuntu repositories?
> 'pip list' just tells me every python package that's installed and
> this really isn't much help.
>
>
> Can one uninstall older versions? For example I seem to have
> three versions of Click installed:-
>
> /usr/local/lib/python2.7/dist-packages/click
> /usr/local/lib/python3.7/dist-packages/click
> /usr/lib/python3/dist-packages/click

Everything under one of these directories comes from apt/dpkg packages.
Packages installed using pip will be installed in a directory called site-packages, not dist-packages

To confirm this you can try?the command `dpkg -S <path>`, which will tell you which package a file belongs to

<snip>
>
> If one updates a package using pip will it move it as appropriate from
> (for example) /usr/local/lib/python3.7 to /usr/local/lib/python3.8?

No, each version of pip will completely ignore any packages installed for a different version of Python
> Can pip (or some other tool) tell me what other python packages depend
> on one I'm considering uninstalling?

pipdeptree can do this
> If there are any tools/utilities one can install to check these things
> out I'd love to know about them.
>
> --
> Chris Green
> ?
> --
> https://mail.python.org/mailman/listinfo/python-list

From pankaj at codeisgreat.org  Tue Dec 29 13:36:32 2020
From: pankaj at codeisgreat.org (Pankaj Jangid)
Date: Wed, 30 Dec 2020 00:06:32 +0530
Subject: How to uninstall python 2 package specifically?
References: <khprbh-9pa3.ln1@esprimo.zbmc.eu>
Message-ID: <m2h7o4mpcf.fsf@codeisgreat.org>

Chris Green <cl at isbd.net> writes:

> I have two (or maybe even three) versions of Click installed:-
>
> /usr/local/lib/python2.7/dist-packages/click
> /usr/local/lib/python3.7/dist-packages/click
> /usr/lib/python3/dist-packages/click
>
> I run [x]ubuntu.
>
> How can I uninstall those extra versions of click (which have
> presumably been installed by pip, how would I know?).

For python2 package use pip, for python3 packages use pip3.


From rshepard at appl-ecosys.com  Tue Dec 29 15:50:00 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Tue, 29 Dec 2020 12:50:00 -0800 (PST)
Subject: Learning why module will not load
In-Reply-To: <rsfsm8$u4$1@ciao.gmane.io>
References: <alpine.LNX.2.20.2012291007150.9439@salmo.appl-ecosys.com>
 <rsfsm8$u4$1@ciao.gmane.io>
Message-ID: <alpine.LNX.2.20.2012291249060.9439@salmo.appl-ecosys.com>

On Tue, 29 Dec 2020, Terry Reedy wrote:

> Packages have to be installed for a particular Python binary in order for 
> that binary to import the package.

Terry,

I forgot about this as I don't often upgrade Python.

> Those packages apparently are not installed for that 3.9.1 binary.

This will be corrected today.

Thanks.

Stay well,

Rich

From cl at isbd.net  Tue Dec 29 16:02:48 2020
From: cl at isbd.net (Chris Green)
Date: Tue, 29 Dec 2020 21:02:48 +0000
Subject: Is there any way to check/de-cruft/update Python packages
 installed using pip?
References: <77srbh-fgf3.ln1@esprimo.zbmc.eu>
 <fffa2c6f-ed31-4734-a676-a889e3ced0a6@Spark>
 <mailman.567.1609267437.7193.python-list@python.org>
Message-ID: <o4isbh-s371.ln1@esprimo.zbmc.eu>

Matt Wheeler <funkyhat at gmail.com> wrote:
> On 29 Dec 2020, 14:48 +0000, Chris Green <cl at isbd.net>, wrote:
> > I seem to have quite a lot of old python packages installed over the
> > years using pip and would like, if I can. to clear some of them out.
> >
> >
> > Is there any way to tell if a python package was installed by me
> > directly using pip or was installed from the [x]ubuntu repositories?
> > 'pip list' just tells me every python package that's installed and
> > this really isn't much help.
> >
> >
> > Can one uninstall older versions? For example I seem to have
> > three versions of Click installed:-
> >
> > /usr/local/lib/python2.7/dist-packages/click
> > /usr/local/lib/python3.7/dist-packages/click
> > /usr/lib/python3/dist-packages/click
> 
> Everything under one of these directories comes from apt/dpkg packages.
> Packages installed using pip will be installed in a directory called site-packages, 
> not dist-packages 
> 
> To confirm this you can try?the command `dpkg -S <path>`, which will tell 
> you which package a file belongs to 
> 
Aaaahhhhh!!!!  :-)   I hadn't realised *that* was the significance of
dist-packages and site-packages, thank you very much, that helps a
huge amount.


> <snip>
> >
> > If one updates a package using pip will it move it as appropriate from
> > (for example) /usr/local/lib/python3.7 to /usr/local/lib/python3.8?
> 
> No, each version of pip will completely ignore any packages installed for 
> a different version of Python 

Again something I hadn't really understood before but obvious when you
think about it.  Thank you again.

-- 
Chris Green
?

From cl at isbd.net  Tue Dec 29 16:20:17 2020
From: cl at isbd.net (Chris Green)
Date: Tue, 29 Dec 2020 21:20:17 +0000
Subject: I'm finally disentangled from Python 2, thank you everyone
Message-ID: <h5jsbh-v391.ln1@esprimo.zbmc.eu>

Well, it has taken me a while, but I now seem to have finally detached
myself from any Python 2 dependencies on my various systems.

Firstly may I say thank you to everyone who has helped me with this
(and with other issues) here on the Python list, you are a friendly
and helpful group of people.

I run (mostly) xubuntu systems and, as of xubuntu 20.04 Python 2
should have gone.

First I changed all of my code to use Python 3, this was mostly pretty
trivial (like my code in many ways!), the only slightly difficult
areas were the changes to Gtk and the string->bytes thing which I had
a problem with but, with help from here, was sorted fairly easily.

As regards installed software on my laptop it was easy, I don't quite
know when it all went but I didn't have to do anything, the current
xubuntu 20.10 installation has no Python 2 on it at all.

On my desktop machine it was a bit more difficult because of the Oki
scanner utility which I have asked about quite a lot here.  It has a
.so file built for Python 2 which I couldn't convert.  In the end
(following ideas from here) I have packaged it using cx-freeze so that
the utility and all the libraries etc. that it needs are run 'as a
package' with all the old Python 2 dependencies inside the package. It
took me a while to get it all packaged but it is now done and the
utility runs successfully on my desktop which is 'Python 2 free'
(except of course for files within the Oki utility package).

Phew! :-)


... and thanks again for all the help and support here.

-- 
Chris Green
?

From barry at barrys-emacs.org  Tue Dec 29 16:50:21 2020
From: barry at barrys-emacs.org (Barry)
Date: Tue, 29 Dec 2020 21:50:21 +0000
Subject: Learning why module will not load
In-Reply-To: <alpine.LNX.2.20.2012291007150.9439@salmo.appl-ecosys.com>
References: <alpine.LNX.2.20.2012291007150.9439@salmo.appl-ecosys.com>
Message-ID: <DD090CF2-E058-4717-8D65-CE36A562C548@barrys-emacs.org>



> On 29 Dec 2020, at 18:14, Rich Shepard <rshepard at appl-ecosys.com> wrote:
> 
> ?Running Slackware-14.2/x86_64 and python-3.9.1. Installed are
> six-1.14.0-x86_64-1_SBo and python3-six-1.13.0-x86_64-1_SBo (I don't know if
> the latter is required because six is supposed to be available for python2
> and python3.)
> 
> However, python3 doesn't find either one:
> 
> $ python3
> Python 3.9.1 (default, Dec 26 2020, 11:21:00) [GCC 5.5.0] on linux
> Type "help", "copyright", "credits" or "license" for more information.
>>>> import six
> Traceback (most recent call last):
>  File "<stdin>", line 1, in <module>
> ModuleNotFoundError: No module named 'six'
>>>> import python3_six
> Traceback (most recent call last):
>  File "<stdin>", line 1, in <module>
> ModuleNotFoundError: No module named 'python3_six'
> 
> How do I diagnose why neither module is found?

I do this to to debug odd import issues:

$ python3.9 -v
...
>>> import six

The output will show the attempts python makes to find the six module.

Barry

> 
> TIA,
> 
> Rich
> 
> 
> -- 
> https://mail.python.org/mailman/listinfo/python-list
> 


From rshepard at appl-ecosys.com  Tue Dec 29 17:13:30 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Tue, 29 Dec 2020 14:13:30 -0800 (PST)
Subject: Learning why module will not load
In-Reply-To: <DD090CF2-E058-4717-8D65-CE36A562C548@barrys-emacs.org>
References: <alpine.LNX.2.20.2012291007150.9439@salmo.appl-ecosys.com>
 <DD090CF2-E058-4717-8D65-CE36A562C548@barrys-emacs.org>
Message-ID: <alpine.LNX.2.20.2012291412050.9439@salmo.appl-ecosys.com>

On Tue, 29 Dec 2020, Barry wrote:

> I do this to to debug odd import issues:
> $ python3.9 -v
> ...
>>>> import six
> The output will show the attempts python makes to find the six module.

Barry,

Thank you. It's not finding six and I am rebuilding all python3 packages
since almost none were build using python-3.9.1.

Stay well,

Rich

From cs at cskk.id.au  Tue Dec 29 18:11:19 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Wed, 30 Dec 2020 10:11:19 +1100
Subject: I'm finally disentangled from Python 2, thank you everyone
In-Reply-To: <h5jsbh-v391.ln1@esprimo.zbmc.eu>
References: <h5jsbh-v391.ln1@esprimo.zbmc.eu>
Message-ID: <X+u3lzLdP8VxEkGz@cskk.homeip.net>

On 29Dec2020 21:20, Chris Green <cl at isbd.net> wrote:
>Well, it has taken me a while, but I now seem to have finally detached
>myself from any Python 2 dependencies on my various systems.
[...]
>On my desktop machine it was a bit more difficult because of the Oki
>scanner utility which I have asked about quite a lot here.  It has a
>.so file built for Python 2 which I couldn't convert.  In the end
>(following ideas from here) I have packaged it using cx-freeze so that
>the utility and all the libraries etc. that it needs are run 'as a
>package' with all the old Python 2 dependencies inside the package.  
>[...]

Could I ask you to write up a post on what you did here? I've never used 
cx-freeze but it sounds like a useful thing for keeping legacy stuff 
functioning. A writeup from someone who's actually used it for that 
would be welcome.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From cl at isbd.net  Wed Dec 30 05:58:42 2020
From: cl at isbd.net (Chris Green)
Date: Wed, 30 Dec 2020 10:58:42 +0000
Subject: I'm finally disentangled from Python 2, thank you everyone
References: <h5jsbh-v391.ln1@esprimo.zbmc.eu>
 <X+u3lzLdP8VxEkGz@cskk.homeip.net>
 <mailman.573.1609283490.7193.python-list@python.org>
Message-ID: <243ubh-lr94.ln1@esprimo.zbmc.eu>

> Could I ask you to write up a post on what you did here? I've never used 
> cx-freeze but it sounds like a useful thing for keeping legacy stuff 
> functioning. A writeup from someone who's actually used it for that 
> would be welcome.
> 
Of course, here is what I wrote in my 'self help' Dokuwiki wiki about it. It refers
specifically to the OKI software I wanted to keep using but it should be fairly
easy to apply a similar process to other software.


    I asked on the Python newsgroup and the one suggestion that seemed feasible was to
    package the OKI software with all its dependencies on a system which still has Gtk2
    and Python 2 and then install the whole package on esprimo.

    After a bit of looking around at Snap, Appimage and such I found cx_freeze which is
    aimed specifically at Python.  The latest version doesn't support Python 2 but 5.1.1
    does, so this is how I've have done it....

      * Install xubuntu 18.04 on my old Revo system (has to be 64-bit), 18.04 is still in support. (has to be 64-bit simply because the final target is 64-bit)
      * Install cx_freeze 5.1.1 on Revo
      * Install the Oki software on Revo, check that it works, pulls in lots of libraries and packages.
      * Run 'cxfreeze /usr/libexec/okimfputl/scantool.py' (scantool.py is the utility I want to run on systems without Python 2)
      * Copy the resulting 'dist' directory to the target system, name isn't critical

    Then the fun starts.  There's quite a few more libraries and packages are required
    and the scan daemon needs to be runnable.  (The scan daemon was, fortunately, just
    a compiled program so ran 'as is' without issues)

    Files needed in /usr/libexec/okimfputl and /usr/libexec/okimfpdrv
    """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
    There are a lot of hard coded references to /usr/libexec/okimfputl and
    /usr/libexec/okimfpdrv, it **might** be possible to change all these but
    I decided it would be less painful to use a couple of symbolic links
    to locations in /usr/local/libexec and put the required files in
    /usr/local/libexec/okimfputl and /usr/local/libexec/okimfpdrv.

    I discovered what files are needed in these directories by simply running
    scantool on the target and fixing each error as it arose.

    Other Python package and library files
    """""""""""""""""""""""""""""""""""""
    I have installed the "dist" created by cxfreeze in /usr/local/libexec/okicxfreeze. The executable to run is thus /usr/local/libexec/okicxfreeze/scantool.

    There are also a few .so libraries and Python packages needed, as above I
    just found these by running scantool and fixing each error as it appeared.
    The system library files are put in /usr/local/lib, you have to run ldconfig
    after each file is put there.  The Python packages (including the dreaded
    pyscand.so) have to be put in the working directory when scantool is run,
    so I have put them in /usr/local/libexec/okicxfreeze where the scantool
    executable is.


I hope the above is useful.  As I said it refers specifically to the scantool.py
that I needed for my Oki scanner but I think the description is general enough to
be useful.

The basic process is:-

    Find (or create) a system where the software you want to run works OK.

    Install cx-freeze 5.1.1 on that system and run 'cxfreeze <thing you want to run>'

    Check that the executable created by cxfreeze works on the system you built it on

    Copy the executable (and its 'dist' environment) to the target where you want to run it

    Try and run it on the target

    Iteratively work through the errors it throws up when you run it, in my case these were:-

        Missing .so system library files, copy them from the build system to somewhere
        they will be found on the target.  You could put them in a 'private to the
        package' directory and set LD_LIBRARY_PATH or do as I did and put them in
        a standard library location (and run ldconfig after adding each).

        Missing Python packages, in my case this included the dreaded pyscand.so, I
        just put them in the 'package' directory with the executable and in the
        script that calls the executable set the directory so they are found.

        Data files.  In my case these had locations which were hard coded into all
        the various scripts along with scantool.py.  I *could* have changed all the
        code before building but that would have been a bit messy and error prone
        and there was no guarantee that there weren't some addresses hard coded in
        the executable files and libraries so I just (as you can see above) set up
        the required directories and put the required files there.  In my case this
        was just three or four configuration files and four .png image files.

    Note: It seems that what cxfreeze does is to create the *Python* environment needed
    to run a program.  It assumes that standard system .so files will be available
    on the target (e.g. libc etc.).  It doesn't check to see if any 'non-standard'
    .so files are needed.  The ones I had to copy across were all specific Oki
    ones that came with the Oki utility software.  I'm not quite clear why there
    were (just two) Python package files that didn't get included - one was
    pyscand.so (maybe because it was a .so) the other was a .py though.


If anyone wants further information or clarification feel free to ask, here or
direct to my E-Mail if you want, though keeping it here makes sense so everyone
can benefit.

-- 
Chris Green
?

From as at sci.fi  Wed Dec 30 02:28:14 2020
From: as at sci.fi (Anssi Saari)
Date: Wed, 30 Dec 2020 09:28:14 +0200
Subject: Why do I have both /usr/lib/python3 and /usr/lib/python3.8?
References: <9ftrbh-97i3.ln1@esprimo.zbmc.eu>
Message-ID: <sm01rf7ah2p.fsf@lakka.kapsi.fi>

Chris Green <cl at isbd.net> writes:

> Why are there both /usr/lib/python3 and /usr/lib/python3.8 on my
> x[ubuntu] system?

While it's more of an Ubuntu (or Debian) question better asked in some
relevant Linux forum, in the end it's because some package managers
decided to do that. You can use commands like these to see which
packages put stuff in which directory:

dpkg -S /usr/lib/python3.8
dpkg -S /usr/lib/python3

On my Debian system the corresponding output looks like this:

$ dpkg -S /usr/lib/python3.7
python3.7, libpython3.7-minimal:amd64, python3-tk:amd64,
libpython3.7-dev:amd64, libpython3.7-stdlib:amd64, libpython3.7:amd64,
python3-distutils, python3-lib2to3: /usr/lib/python3.7

$ dpkg -S /usr/lib/python3          
python3-scipy, python3-opengl, python3-statsmodels, iotop,
python3-reportlab-accel:amd64, python3-magic, python3-pkg-resources,
python3-kiwisolver, python3.7, python3-pandas-lib, python3-kerberos,
python3-lz4, python3-renderpm:amd64, python3-numexpr,
python3-cffi-backend, python3-crypto, python3-tables, python3-rencode,
python3-gi, python3-dbus, devscripts, python3-gpg, python3-pyasn1,
python3-py, python3-eyed3, pdfarranger, python3-pip, python3-virtualenv,
xpra, python3-pandas, python3-pil:amd64, python3-requests,
python3-urllib3, python3-psutil, python3-paramiko, python3-netifaces,
python3-patsy, python3-gssapi, python3-sklearn, python3-cycler,
python3-sip, python3-cairo:amd64, python3-six, python3-chardet,
python3-nose, python3-debian, python3-wheel, python3-attr,
python3-soupsieve, python3-bcrypt, python3-bs4, python3-sklearn-lib,
python3-scour, python3-setuptools, python3-entrypoints,
python3-gi-cairo, python3-cups, python3-keyrings.alt, python3-pluggy,
python3-tz, python3-ifaddr, python3-joblib, python3-cvxopt,
python3-secretstorage, python3-reportlab, python3-more-itertools,
python3-keyring, python3-asn1crypto, python3-html5lib, python3-dns,
python3-decorator, python3-dateutil, meson, python3-pexpect,
python3-idna, python3-seaborn, lsb-release, python3-numpy,
python3-brotli, python3-tables-lib, python3-lxml:amd64, python3-pytest,
python3-simplejson, python3-nacl, python3-zeroconf, python3-xdg,
python3-libvoikko, python3-gst-1.0, python3-pypdf2, python3-evdev,
python3-matplotlib, python3-statsmodels-lib, python3-cryptography,
python3-certifi, python3-atomicwrites, python3-pyparsing,
python3-ptyprocess, python3-webencodings, piper, python3-uno,
python3-apt, python3-setproctitle:amd64, hplip: /usr/lib/python3

So I'd say as a rule stuff relevant to the specific version of python
goes in the specific version directory (i.e. /usr/lib/python3.8 in your
case) and python software packages in general go in /usr/lib/python3.


From cl at isbd.net  Wed Dec 30 12:02:37 2020
From: cl at isbd.net (Chris Green)
Date: Wed, 30 Dec 2020 17:02:37 +0000
Subject: Why do I have both /usr/lib/python3 and /usr/lib/python3.8?
References: <9ftrbh-97i3.ln1@esprimo.zbmc.eu> <sm01rf7ah2p.fsf@lakka.kapsi.fi>
 <mailman.574.1609345144.7193.python-list@python.org>
Message-ID: <deoubh-c55.ln1@esprimo.zbmc.eu>

Anssi Saari <as at sci.fi> wrote:
> Chris Green <cl at isbd.net> writes:
> 
> > Why are there both /usr/lib/python3 and /usr/lib/python3.8 on my
> > x[ubuntu] system?
> 
> While it's more of an Ubuntu (or Debian) question better asked in some
> relevant Linux forum, in the end it's because some package managers
> decided to do that. You can use commands like these to see which
> packages put stuff in which directory:
> 
> dpkg -S /usr/lib/python3.8
> dpkg -S /usr/lib/python3
> 
> On my Debian system the corresponding output looks like this:
> 
> $ dpkg -S /usr/lib/python3.7
> python3.7, libpython3.7-minimal:amd64, python3-tk:amd64,
> libpython3.7-dev:amd64, libpython3.7-stdlib:amd64, libpython3.7:amd64,
> python3-distutils, python3-lib2to3: /usr/lib/python3.7
> 
> $ dpkg -S /usr/lib/python3          
> python3-scipy, python3-opengl, python3-statsmodels, iotop,
> python3-reportlab-accel:amd64, python3-magic, python3-pkg-resources,
> python3-kiwisolver, python3.7, python3-pandas-lib, python3-kerberos,
> python3-lz4, python3-renderpm:amd64, python3-numexpr,
> python3-cffi-backend, python3-crypto, python3-tables, python3-rencode,
> python3-gi, python3-dbus, devscripts, python3-gpg, python3-pyasn1,
> python3-py, python3-eyed3, pdfarranger, python3-pip, python3-virtualenv,
> xpra, python3-pandas, python3-pil:amd64, python3-requests,
> python3-urllib3, python3-psutil, python3-paramiko, python3-netifaces,
> python3-patsy, python3-gssapi, python3-sklearn, python3-cycler,
> python3-sip, python3-cairo:amd64, python3-six, python3-chardet,
> python3-nose, python3-debian, python3-wheel, python3-attr,
> python3-soupsieve, python3-bcrypt, python3-bs4, python3-sklearn-lib,
> python3-scour, python3-setuptools, python3-entrypoints,
> python3-gi-cairo, python3-cups, python3-keyrings.alt, python3-pluggy,
> python3-tz, python3-ifaddr, python3-joblib, python3-cvxopt,
> python3-secretstorage, python3-reportlab, python3-more-itertools,
> python3-keyring, python3-asn1crypto, python3-html5lib, python3-dns,
> python3-decorator, python3-dateutil, meson, python3-pexpect,
> python3-idna, python3-seaborn, lsb-release, python3-numpy,
> python3-brotli, python3-tables-lib, python3-lxml:amd64, python3-pytest,
> python3-simplejson, python3-nacl, python3-zeroconf, python3-xdg,
> python3-libvoikko, python3-gst-1.0, python3-pypdf2, python3-evdev,
> python3-matplotlib, python3-statsmodels-lib, python3-cryptography,
> python3-certifi, python3-atomicwrites, python3-pyparsing,
> python3-ptyprocess, python3-webencodings, piper, python3-uno,
> python3-apt, python3-setproctitle:amd64, hplip: /usr/lib/python3
> 
> So I'd say as a rule stuff relevant to the specific version of python
> goes in the specific version directory (i.e. /usr/lib/python3.8 in your
> case) and python software packages in general go in /usr/lib/python3.
> 
Yes, there are some oddities though, for example python3.7 seems to be
installed in both locations (python3.8 in my case).

-- 
Chris Green
?

From auriocus at gmx.de  Wed Dec 30 12:39:34 2020
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Wed, 30 Dec 2020 18:39:34 +0100
Subject: I'm finally disentangled from Python 2, thank you everyone
In-Reply-To: <243ubh-lr94.ln1@esprimo.zbmc.eu>
References: <h5jsbh-v391.ln1@esprimo.zbmc.eu>
 <X+u3lzLdP8VxEkGz@cskk.homeip.net>
 <mailman.573.1609283490.7193.python-list@python.org>
 <243ubh-lr94.ln1@esprimo.zbmc.eu>
Message-ID: <rsie0m$kan$1@dont-email.me>

Am 30.12.20 um 11:58 schrieb Chris Green:
>> Could I ask you to write up a post on what you did here? I've never used
>> cx-freeze but it sounds like a useful thing for keeping legacy stuff
>> functioning. A writeup from someone who's actually used it for that
>> would be welcome.
>>
> Of course, here is what I wrote in my 'self help' Dokuwiki wiki about it. It refers
> specifically to the OKI software I wanted to keep using but it should be fairly
> easy to apply a similar process to other software.
> 
> 
>      I asked on the Python newsgroup and the one suggestion that seemed feasible was to
>      package the OKI software with all its dependencies on a system which still has Gtk2
>      and Python 2 and then install the whole package on esprimo.
> 
>      After a bit of looking around at Snap, Appimage and such I found cx_freeze which is
>      aimed specifically at Python.  The latest version doesn't support Python 2 but 5.1.1
>      does, so this is how I've have done it....
> 
>        * Install xubuntu 18.04 on my old Revo system (has to be 64-bit), 18.04 is still in support. (has to be 64-bit simply because the final target is 64-bit)
>        * Install cx_freeze 5.1.1 on Revo
>        * Install the Oki software on Revo, check that it works, pulls in lots of libraries and packages.
>        * Run 'cxfreeze /usr/libexec/okimfputl/scantool.py' (scantool.py is the utility I want to run on systems without Python 2)
>        * Copy the resulting 'dist' directory to the target system, name isn't critical
> 
>      Then the fun starts.  There's quite a few more libraries and packages are required
>      and the scan daemon needs to be runnable.  (The scan daemon was, fortunately, just
>      a compiled program so ran 'as is' without issues)
> 
>      Files needed in /usr/libexec/okimfputl and /usr/libexec/okimfpdrv
>      """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
>      There are a lot of hard coded references to /usr/libexec/okimfputl and
>      /usr/libexec/okimfpdrv, it **might** be possible to change all these but
>      I decided it would be less painful to use a couple of symbolic links
>      to locations in /usr/local/libexec and put the required files in
>      /usr/local/libexec/okimfputl and /usr/local/libexec/okimfpdrv.
> 
>      I discovered what files are needed in these directories by simply running
>      scantool on the target and fixing each error as it arose.
> 
>      Other Python package and library files
>      """""""""""""""""""""""""""""""""""""
>      I have installed the "dist" created by cxfreeze in /usr/local/libexec/okicxfreeze. The executable to run is thus /usr/local/libexec/okicxfreeze/scantool.
> 
>      There are also a few .so libraries and Python packages needed, as above I
>      just found these by running scantool and fixing each error as it appeared.
>      The system library files are put in /usr/local/lib, you have to run ldconfig
>      after each file is put there.  The Python packages (including the dreaded
>      pyscand.so) have to be put in the working directory when scantool is run,
>      so I have put them in /usr/local/libexec/okicxfreeze where the scantool
>      executable is.
> 
> 
> I hope the above is useful.  As I said it refers specifically to the scantool.py
> that I needed for my Oki scanner but I think the description is general enough to
> be useful.
> 
> The basic process is:-
> 
>      Find (or create) a system where the software you want to run works OK.
> 
>      Install cx-freeze 5.1.1 on that system and run 'cxfreeze <thing you want to run>'
> 
>      Check that the executable created by cxfreeze works on the system you built it on
> 
>      Copy the executable (and its 'dist' environment) to the target where you want to run it
> 
>      Try and run it on the target
> 
>      Iteratively work through the errors it throws up when you run it, in my case these were:-
> 
>          Missing .so system library files, copy them from the build system to somewhere
>          they will be found on the target.  You could put them in a 'private to the
>          package' directory and set LD_LIBRARY_PATH or do as I did and put them in
>          a standard library location (and run ldconfig after adding each).


I've used pyinstaller in the past, and it seems to do a better job with 
that. It usually copies all the sytem libraries, too, but would fail 
with /usr/libexec/okimfputl  & friends

	Christian


From markbdusted at gmail.com  Wed Dec 30 13:35:18 2020
From: markbdusted at gmail.com (Mark Bachman)
Date: Wed, 30 Dec 2020 13:35:18 -0500
Subject: bCNC
Message-ID: <CANgi-5n_0Pq0TkAGRv-NMkxViLNcHE9tw3J_DPe4bmVOekj1_w@mail.gmail.com>

I have installed Python 3.9.0 and 3.9.1 in an effort to install bCNC.
After entering the cmd prompt for installing bCNC the reply indicates
intsall was successful.
However when trying to launch bCNC with command prompt I get the following
reply.
Microsoft Windows [Version 10.0.19041.685]
(c) 2020 Microsoft Corporation. All rights reserved.

C:\Users\------------->py -m bCNC
new-config Utils <configparser.ConfigParser object at 0x000001170C96B0D0>
 ** On entry to DGEBAL parameter number  3 had an illegal value
 ** On entry to DGEHRD  parameter number  2 had an illegal value
 ** On entry to DORGHR DORGQR parameter number  2 had an illegal value
 ** On entry to DHSEQR parameter number  4 had an illegal value
Traceback (most recent call last):
  File
"C:\Users\--------\AppData\Local\Programs\Python\Python39\lib\runpy.py",
line 197, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File
"C:\Users\---------\AppData\Local\Programs\Python\Python39\lib\runpy.py",
line 87, in _run_code
    exec(code, run_globals)
  File
"C:\Users\----------\AppData\Local\Programs\Python\Python39\lib\site-packages\bCNC\__main__.py",
line 60, in <module>
    from CNC import WAIT, CNC, GCode
  File
"C:\Users\-----------\AppData\Local\Programs\Python\Python39\lib\site-packages\bCNC\CNC.py",
line 25, in <module>
    from svgcode        import SVGcode
  File
"C:\Users\---------\AppData\Local\Programs\Python\Python39\lib\site-packages\bCNC\lib\svgcode.py",
line 13, in <module>
    import numpy
  File
"C:\Users\---------\AppData\Local\Programs\Python\Python39\lib\site-packages\numpy\__init__.py",
line 305, in <module>
    _win_os_check()
  File
"C:\Users\-----------\AppData\Local\Programs\Python\Python39\lib\site-packages\numpy\__init__.py",
line 302, in _win_os_check
    raise RuntimeError(msg.format(__file__)) from None
RuntimeError: The current Numpy installation
('C:\\Users\\----------\\AppData\\Local\\Programs\\Python\\Python39\\lib\\site-packages\\numpy\\__init__.py')
fails to pass a sanity check due to a bug in the windows runtime. See this
issue for more information: https://tinyurl.com/y3dm3h86

C:\Users\-------------->

Any help would be greatly appreciated.

-- 
Thanks
Mark Bachman

People love chopping wood. In this activity one immediately sees results.
<http://www.brainyquote.com/quotes/quotes/a/alberteins108301.html>
Albert Einstein
<http://www.brainyquote.com/quotes/quotes/a/alberteins108301.html>

From rshepard at appl-ecosys.com  Wed Dec 30 14:12:50 2020
From: rshepard at appl-ecosys.com (Rich Shepard)
Date: Wed, 30 Dec 2020 11:12:50 -0800 (PST)
Subject: ipython missing required module with python-3.9.1
Message-ID: <alpine.LNX.2.20.2012301104130.30809@salmo.appl-ecosys.com>

Using the installed Python3-3.9.1 I rebuilt all python3 modules, including
python3-prompt_toolkit-3.0.8, python3-ipython-7.19.0, and ipython_genutils.

Trying to invoke ipython results in a not-found module:
$ ipython
Traceback (most recent call last):
   File "/usr/bin/ipython", line 4, in <module>
     from IPython import start_ipython
   File "/usr/lib64/python3.9/site-packages/IPython/__init__.py", line 56, in <module>
     from .terminal.embed import embed
   File "/usr/lib64/python3.9/site-packages/IPython/terminal/embed.py", line 16, in <module>
     from IPython.terminal.interactiveshell import TerminalInteractiveShell
   File "/usr/lib64/python3.9/site-packages/IPython/terminal/interactiveshell.py", line 21, in <module>
     from prompt_toolkit.formatted_text import PygmentsTokens
ModuleNotFoundError: No module named 'prompt_toolkit.formatted_text'

Running python3 from the command line I see there is no formatted_text in
prompt_toolkit:
>>> dir(prompt_toolkit)
['AbortAction', 'Application', 'CommandLineInterface', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__path__', '__spec__', '__version__', 'application', 'auto_suggest', 'buffer', 'buffer_mapping', 'cache', 'clipboard', 'completion', 'document', 'enums', 'eventloop', 'filters', 'history', 'input', 'interface', 'key_binding', 'keys', 'layout', 'mouse_events', 'output', 'prompt', 'prompt_async', 'reactive', 'renderer', 'search_state', 'selection', 'shortcuts', 'styles', 'terminal', 'token', 'utils', 'validation']
>>> from prompt_toolkit import formatted_text
Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
ImportError: cannot import name 'formatted_text' from 'prompt_toolkit' (/usr/lib64/python3.9/site-packages/prompt_toolkit/__init__.py)

What am I missing here?

TIA,

Rich


From python at mrabarnett.plus.com  Wed Dec 30 15:10:24 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Wed, 30 Dec 2020 20:10:24 +0000
Subject: bCNC
In-Reply-To: <CANgi-5n_0Pq0TkAGRv-NMkxViLNcHE9tw3J_DPe4bmVOekj1_w@mail.gmail.com>
References: <CANgi-5n_0Pq0TkAGRv-NMkxViLNcHE9tw3J_DPe4bmVOekj1_w@mail.gmail.com>
Message-ID: <e5ce7900-be9a-edc0-f7a6-806b6ba66a10@mrabarnett.plus.com>

On 2020-12-30 18:35, Mark Bachman wrote:
> I have installed Python 3.9.0 and 3.9.1 in an effort to install bCNC.
> After entering the cmd prompt for installing bCNC the reply indicates
> intsall was successful.
> However when trying to launch bCNC with command prompt I get the following
> reply.
> Microsoft Windows [Version 10.0.19041.685]
> (c) 2020 Microsoft Corporation. All rights reserved.
> 
> C:\Users\------------->py -m bCNC
> new-config Utils <configparser.ConfigParser object at 0x000001170C96B0D0>
>   ** On entry to DGEBAL parameter number  3 had an illegal value
>   ** On entry to DGEHRD  parameter number  2 had an illegal value
>   ** On entry to DORGHR DORGQR parameter number  2 had an illegal value
>   ** On entry to DHSEQR parameter number  4 had an illegal value
> Traceback (most recent call last):
>    File
> "C:\Users\--------\AppData\Local\Programs\Python\Python39\lib\runpy.py",
> line 197, in _run_module_as_main
>      return _run_code(code, main_globals, None,
>    File
> "C:\Users\---------\AppData\Local\Programs\Python\Python39\lib\runpy.py",
> line 87, in _run_code
>      exec(code, run_globals)
>    File
> "C:\Users\----------\AppData\Local\Programs\Python\Python39\lib\site-packages\bCNC\__main__.py",
> line 60, in <module>
>      from CNC import WAIT, CNC, GCode
>    File
> "C:\Users\-----------\AppData\Local\Programs\Python\Python39\lib\site-packages\bCNC\CNC.py",
> line 25, in <module>
>      from svgcode        import SVGcode
>    File
> "C:\Users\---------\AppData\Local\Programs\Python\Python39\lib\site-packages\bCNC\lib\svgcode.py",
> line 13, in <module>
>      import numpy
>    File
> "C:\Users\---------\AppData\Local\Programs\Python\Python39\lib\site-packages\numpy\__init__.py",
> line 305, in <module>
>      _win_os_check()
>    File
> "C:\Users\-----------\AppData\Local\Programs\Python\Python39\lib\site-packages\numpy\__init__.py",
> line 302, in _win_os_check
>      raise RuntimeError(msg.format(__file__)) from None
> RuntimeError: The current Numpy installation
> ('C:\\Users\\----------\\AppData\\Local\\Programs\\Python\\Python39\\lib\\site-packages\\numpy\\__init__.py')
> fails to pass a sanity check due to a bug in the windows runtime. See this
> issue for more information: https://tinyurl.com/y3dm3h86
> 
> C:\Users\-------------->
> 
> Any help would be greatly appreciated.
> 
Did you read the page at https://tinyurl.com/y3dm3h86?

Basically, it's a known bug. Use numpy 1.19.3 instead of numpy 1.19.4:

py -m pip uninstall numpy
py -m pip install numpy==1.19.3

From mishazakacura at gmail.com  Wed Dec 30 16:14:26 2020
From: mishazakacura at gmail.com (BearGod777)
Date: Wed, 30 Dec 2020 21:14:26 +0000
Subject: help
Message-ID: <CAJPJpF_8q8KS1BMMU8J0ZfYBSks1Y0LVnAMcJefkASK3hF--8w@mail.gmail.com>

every time i try and open a .py file it just ciomes up with either modify,
uninstall or repair. i have tried every single one of these and i have
tried to install another version (it couldnt run on that version) and it
just doesnt load up. if i try and open a new file it works but if i try and
open a file that my friend made it just comes up with those options. please
help
ReplyForward

From ikorot01 at gmail.com  Wed Dec 30 18:19:00 2020
From: ikorot01 at gmail.com (Igor Korot)
Date: Wed, 30 Dec 2020 17:19:00 -0600
Subject: help
In-Reply-To: <CAJPJpF_8q8KS1BMMU8J0ZfYBSks1Y0LVnAMcJefkASK3hF--8w@mail.gmail.com>
References: <CAJPJpF_8q8KS1BMMU8J0ZfYBSks1Y0LVnAMcJefkASK3hF--8w@mail.gmail.com>
Message-ID: <CA+FnnTy2xd_Ufv7BoY-b_+3mduqkQmC15xX4yApGZRQDzPBnYw@mail.gmail.com>

Hi,

On Wed, Dec 30, 2020 at 4:40 PM BearGod777 <mishazakacura at gmail.com> wrote:
>
> every time i try and open a .py file

How are you trying to open the py file?
Also - I presume you are using Windows 10 + latest version of python, right?

Thank you.

> ReplyForward
> --
> https://mail.python.org/mailman/listinfo/python-list

From Bischoop at vimart.net  Wed Dec 30 18:20:08 2020
From: Bischoop at vimart.net (Bischoop)
Date: Wed, 30 Dec 2020 23:20:08 -0000 (UTC)
Subject: Which method to check if string index is queal to character.
References: <slrnruk235.79g.Bischoop@vimart.net>
 <CABbU2U8XxzdQ_i=gS57ix0UmsvMdOPWmR8yLxdtieFDpY8kUNw@mail.gmail.com>
 <c0458de8-c38c-24be-9f63-cdb94f43e28a@wichmann.us>
 <mailman.547.1609186156.7193.python-list@python.org>
 <slrnrul2n0.h12.Bischoop@vimart.net> <rseu9r$14c7$1@gioia.aioe.org>
Message-ID: <slrnruq2p8.2gq.Bischoop@vimart.net>

On 2020-12-29, jak <nospam at please.ty> wrote:
>
> you could try this way:
>
> # -----------
> from dns import resolver as dns
>
> emails=['john.doe at fakeserver.bah',
>          'john.doe at gmail.com']
>
> for ue in emails:
>      try:
>          mxl = dns.resolve(ue.split('@')[1], 'MX')
>      except:
>          print(f'{ue}: bad mail server')
>      else:
>          if len(mxl) > 0:
>              print(f'{ue}: valid mail server')
> # -----------
>
> ... so, having verified the sever, you should only worry about the name.

I actually have tried, that's good idea.

--
Thanks

From mats at wichmann.us  Wed Dec 30 19:51:57 2020
From: mats at wichmann.us (Mats Wichmann)
Date: Wed, 30 Dec 2020 17:51:57 -0700
Subject: help
In-Reply-To: <CAJPJpF_8q8KS1BMMU8J0ZfYBSks1Y0LVnAMcJefkASK3hF--8w@mail.gmail.com>
References: <CAJPJpF_8q8KS1BMMU8J0ZfYBSks1Y0LVnAMcJefkASK3hF--8w@mail.gmail.com>
Message-ID: <ff34e6c7-aa2b-7bad-7edc-77f17bb0ed9b@wichmann.us>

On 12/30/20 2:14 PM, BearGod777 wrote:
> every time i try and open a .py file it just ciomes up with either modify,
> uninstall or repair. i have tried every single one of these and i have
> tried to install another version (it couldnt run on that version) and it
> just doesnt load up. if i try and open a new file it works but if i try and
> open a file that my friend made it just comes up with those options. please
> help

you're rerunning the installer, don't do that.

that sounds rude. but isn't meant to be.  somehow in recent times, the 
installer program - whose job it is indeed to install, uninstall, repair 
- is getting picked up by Windows when you try to run Python in certain 
ways - the installer should certainly not be getting associated with .py 
files as the way to run them. It might help diagnose how this happens if 
you describe what you're doing ("try and open a .py file" doesn't say 
enough, how are you trying to open it?)

open a command shell (cmd.exe or powershell) and run your script foo.py 
with "py foo.py", assuming you chose to install the Python Launcher, 
which you should do if using the Python that comes from python.org.




From khoroshyy at gmail.com  Thu Dec 31 05:43:22 2020
From: khoroshyy at gmail.com (Petro)
Date: Thu, 31 Dec 2020 02:43:22 -0800 (PST)
Subject: Control stript which is runing in background.
Message-ID: <5d0d4112-3473-4248-8ffe-271c35e081c5n@googlegroups.com>

Hi. 
I would like to make something like this:
A python script would run headlessly in the background.
I would like to control the script from the command line using other python scripts or from the python shell.
>From time to time I would ask the main script to create a popup window with an image or a plot.
What would be the proper way to approach it. How to make communication between two scripts?
Thank you.
Petro.

From python at mrabarnett.plus.com  Thu Dec 31 07:29:06 2020
From: python at mrabarnett.plus.com (MRAB)
Date: Thu, 31 Dec 2020 12:29:06 +0000
Subject: Control stript which is runing in background.
In-Reply-To: <5d0d4112-3473-4248-8ffe-271c35e081c5n@googlegroups.com>
References: <5d0d4112-3473-4248-8ffe-271c35e081c5n@googlegroups.com>
Message-ID: <052a1bff-46ff-0cd1-10c7-87b4053b2199@mrabarnett.plus.com>

On 2020-12-31 10:43, Petro wrote:
> Hi.
> I would like to make something like this:
> A python script would run headlessly in the background.
> I would like to control the script from the command line using other python scripts or from the python shell.
>   From time to time I would ask the main script to create a popup window with an image or a plot.
> What would be the proper way to approach it. How to make communication between two scripts?
> 
For communication, a socket would work. There are examples of a simple 
socket server and a simple socket client in the Python docs for the 
'socket' module.

From garabik-news-2005-05 at kassiopeia.juls.savba.sk  Thu Dec 31 09:36:06 2020
From: garabik-news-2005-05 at kassiopeia.juls.savba.sk (garabik-news-2005-05 at kassiopeia.juls.savba.sk)
Date: Thu, 31 Dec 2020 14:36:06 +0000 (UTC)
Subject: ANN: unicode 2.8
Message-ID: <rsknkm$oke$1@gioia.aioe.org>

unicode is a simple python command line utility that displays
properties for a given unicode character, or searches
unicode database for a given name.

It was written with Linux in mind, but should work almost everywhere
(including MS Windows and MacOSX), UTF-8 console is recommended.

?p??pu??s ?po???u? ??? ?o ?sn p??u??p?
pu? s?ld???u???d ??? ?u??????suo??p loo? ??????p??p ?u?ll??x? u? s?? ?I
?s?u??od?po? ?u???????p ?l???ld?o? ?u??sn ?l???? 's?d?l? ?o ?????s ??l?????s
?ll?ns???  o?u?? ?x?? ??? ????uo? o? p??pu??s ?po???u? ??? ?o ???od lln?
??? s???oldx? ???? '????l???n ,?po????d, osl? su????uo? ??????d ???

Changes since previous versions:

 * display ASCII table (either traditional with --ascii or the new
   EU?UK Trade and Cooperation Agreement version with --brexit-ascii)
 * minor bug fixes

URL: http://kassiopeia.juls.savba.sk/~garabik/software/unicode.html

License: GPL v3

Installation: pip install unicode

-- 
 -----------------------------------------------------------
| Radovan Garab?k http://kassiopeia.juls.savba.sk/~garabik/ |
| __..--^^^--..__    garabik @ kassiopeia.juls.savba.sk     |
 -----------------------------------------------------------
Antivirus alert: file .signature infected by signature virus.
Hi! I'm a signature virus! Copy me into your signature file to help me spread!

From mishazakacura at gmail.com  Thu Dec 31 10:11:01 2020
From: mishazakacura at gmail.com (BearGod777)
Date: Thu, 31 Dec 2020 15:11:01 +0000
Subject: help
In-Reply-To: <ff34e6c7-aa2b-7bad-7edc-77f17bb0ed9b@wichmann.us>
References: <CAJPJpF_8q8KS1BMMU8J0ZfYBSks1Y0LVnAMcJefkASK3hF--8w@mail.gmail.com>
 <ff34e6c7-aa2b-7bad-7edc-77f17bb0ed9b@wichmann.us>
Message-ID: <CAJPJpF9-2FTZAuJpVwkyRu9VtvqiV6pVc51pUB4F7EZ_TGz0AQ@mail.gmail.com>

i am trying to open it by just left clicking the file in file explorer and
i tried right clicking it and then pressing open with python 3.9.1 64-bit

On Thu, 31 Dec 2020 at 00:52, Mats Wichmann <mats at wichmann.us> wrote:

> On 12/30/20 2:14 PM, BearGod777 wrote:
> > every time i try and open a .py file it just ciomes up with either
> modify,
> > uninstall or repair. i have tried every single one of these and i have
> > tried to install another version (it couldnt run on that version) and it
> > just doesnt load up. if i try and open a new file it works but if i try
> and
> > open a file that my friend made it just comes up with those options.
> please
> > help
>
> you're rerunning the installer, don't do that.
>
> that sounds rude. but isn't meant to be.  somehow in recent times, the
> installer program - whose job it is indeed to install, uninstall, repair
> - is getting picked up by Windows when you try to run Python in certain
> ways - the installer should certainly not be getting associated with .py
> files as the way to run them. It might help diagnose how this happens if
> you describe what you're doing ("try and open a .py file" doesn't say
> enough, how are you trying to open it?)
>
> open a command shell (cmd.exe or powershell) and run your script foo.py
> with "py foo.py", assuming you chose to install the Python Launcher,
> which you should do if using the Python that comes from python.org.
>
>
>
>

From mats at wichmann.us  Thu Dec 31 12:06:39 2020
From: mats at wichmann.us (Mats Wichmann)
Date: Thu, 31 Dec 2020 10:06:39 -0700
Subject: help
In-Reply-To: <CAJPJpF9-2FTZAuJpVwkyRu9VtvqiV6pVc51pUB4F7EZ_TGz0AQ@mail.gmail.com>
References: <CAJPJpF_8q8KS1BMMU8J0ZfYBSks1Y0LVnAMcJefkASK3hF--8w@mail.gmail.com>
 <ff34e6c7-aa2b-7bad-7edc-77f17bb0ed9b@wichmann.us>
 <CAJPJpF9-2FTZAuJpVwkyRu9VtvqiV6pVc51pUB4F7EZ_TGz0AQ@mail.gmail.com>
Message-ID: <46b11e77-ac1c-3071-3a07-8b23fb0c898c@wichmann.us>

On 12/31/20 8:11 AM, BearGod777 wrote:
> i am trying to open it by just left clicking the file in file explorer and
> i tried right clicking it and then pressing open with python 3.9.1 64-bit

That *shouldn't* open the installer... (you can actually remove the 
installer file once you're done installing, it can maybe reduce some 
confusion).

What you're doing is going to give you probably unexpected results 
anyway. Here's why:  (when it's set up properly) when clicking from 
explorer Windows will create a window to run the Python interpreter in, 
and when your script finishes, Python quits. Windows will take that as a 
clue that the window is no longer needed, and it will be discarded. This 
will usually have the visual effect of a window flashing onto the screen 
and then vanishing, as if things were broken, but they're not.  Only a 
Python script that is written to manage a display window, is going to 
stay around. An old is to add an input() call at the end of your script, 
so it waits for you to hit the enter key before finishing, and that will 
leave the window open)

Either run your scripts from a command shell...

Or use an editor or IDE that has an integrated way to run your programs 
there in the editor's environment - here the IDE manages the windows so 
you don't get the opens-then-closes effect.

Hope this helps.


From nospam at please.ty  Thu Dec 31 12:07:31 2020
From: nospam at please.ty (jak)
Date: Thu, 31 Dec 2020 18:07:31 +0100
Subject: Control stript which is runing in background.
References: <5d0d4112-3473-4248-8ffe-271c35e081c5n@googlegroups.com>
Message-ID: <rsl0gh$qsv$1@gioia.aioe.org>

Il 31/12/2020 11:43, Petro ha scritto:
> Hi.
> I would like to make something like this:
> A python script would run headlessly in the background.
> I would like to control the script from the command line using other python scripts or from the python shell.
>  From time to time I would ask the main script to create a popup window with an image or a plot.
> What would be the proper way to approach it. How to make communication between two scripts?
> Thank you.
> Petro.
> 

using named pipes would be an alternative. A small example that produces 
an echo for windows. For linux it's simpler using os.mkfifo:

# ---------------------
import win32pipe as wp, win32file as wf

pfile = r'\\.\pipe\mypipe'
how = 0
data: bytes
while True:
     pipe = wp.CreateNamedPipe(pfile, wp.PIPE_ACCESS_DUPLEX,
                               wp.PIPE_TYPE_BYTE | wp.PIPE_READMODE_BYTE 
| wp.PIPE_WAIT,
                               wp.PIPE_UNLIMITED_INSTANCES, 0xffff, 
0xffff, 0, None)
     if pipe:
         wp.ConnectNamedPipe(pipe, None)
         while True:
             try:
                 rv, data = wf.ReadFile(pipe, 1024)
             except:
                 wf.CloseHandle(pipe)
                 break
             else:
                 print(data.decode(), end='')
     else:
         break
# ---------------------

you can pass commands to it this way too:

$> echo "print log" > \\.\pipe\mypipe

From tjreedy at udel.edu  Thu Dec 31 14:50:09 2020
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 31 Dec 2020 14:50:09 -0500
Subject: ANN: unicode 2.8
In-Reply-To: <rsknkm$oke$1__36657.8751521715$1609426306$gmane$org@gioia.aioe.org>
References: <rsknkm$oke$1__36657.8751521715$1609426306$gmane$org@gioia.aioe.org>
Message-ID: <rsla1j$t9t$1@ciao.gmane.io>

On 12/31/2020 9:36 AM, garabik-news-2005-05 at kassiopeia.juls.savba.sk wrote:
> unicode is a simple python command line utility that displays
> properties for a given unicode character, or searches
> unicode database for a given name.
...
> Changes since previous versions:
> 
>   * display ASCII table (either traditional with --ascii or the new
>     EU?UK Trade and Cooperation Agreement version with --brexit-ascii)

Are you reproducing it with bugs included?
How is that of any use to anyone?
A tweet linking the treaty annex page
https://twitter.com/thejsa_/status/1343291595899207681
A stackoverflow question and discussion of the bugs and oddities.
https://politics.stackexchange.com/questions/61178/why-does-the-eu-uk-trade-deal-have-the-7-bit-ascii-table-as-an-appendix

The likely answer is that the treaty writers copy-pasted from 
decades-old docs and could not be bothered to link to the actual ISO 
standard.

-- 
Terry Jan Reedy



From cs at cskk.id.au  Thu Dec 31 16:43:50 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Fri, 1 Jan 2021 08:43:50 +1100
Subject: Control stript which is runing in background.
In-Reply-To: <rsl0gh$qsv$1@gioia.aioe.org>
References: <rsl0gh$qsv$1@gioia.aioe.org>
Message-ID: <X+5GFnXOavnABHTu@cskk.homeip.net>

On 31Dec2020 18:07, jak <nospam at please.ty> wrote:
>Il 31/12/2020 11:43, Petro ha scritto:
>>I would like to make something like this:
>>A python script would run headlessly in the background.
>>I would like to control the script from the command line using other python scripts or from the python shell.
>> From time to time I would ask the main script to create a popup window with an image or a plot.
>>What would be the proper way to approach it. How to make communication between two scripts?
>
>using named pipes would be an alternative. A small example that 
>produces an echo for windows.

A Windows named pipe seems to be more like a UNIX-side "UNIX domain 
socket" than a UNIX side "named pipe".

>For linux it's simpler using os.mkfifo:

Not really. For Linux (and of course other UNIXen) you really want a 
UNIX domain socket, not a a name pipe (as from mkfifo).

The reason is that a socket (and a Windows pipe, from my limited 
understanding) creates a new distinct connection when you open it. (The 
other end has to accept that connection, at least in UNIX).

The problem with a UNIX pipe is that every client (your command line 
control script) _share_ the same pipe - if two scripts un at once there 
will be a failure. If you contrive some locking scheme then you can 
share a named pipe in UNIX because only once client will use the pipe at 
a time.

Just something to keep in mind.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From nospam at please.ty  Thu Dec 31 18:26:09 2020
From: nospam at please.ty (jak)
Date: Fri, 1 Jan 2021 00:26:09 +0100
Subject: Control stript which is runing in background.
References: <rsl0gh$qsv$1@gioia.aioe.org> <X+5GFnXOavnABHTu@cskk.homeip.net>
 <mailman.585.1609451043.7193.python-list@python.org>
Message-ID: <rslmmd$it0$1@gioia.aioe.org>

Il 31/12/2020 22:43, Cameron Simpson ha scritto:
> On 31Dec2020 18:07, jak <nospam at please.ty> wrote:
>> Il 31/12/2020 11:43, Petro ha scritto:
>>> I would like to make something like this:
>>> A python script would run headlessly in the background.
>>> I would like to control the script from the command line using other python scripts or from the python shell.
>>>  From time to time I would ask the main script to create a popup window with an image or a plot.
>>> What would be the proper way to approach it. How to make communication between two scripts?
>>
>> using named pipes would be an alternative. A small example that
>> produces an echo for windows.
> 
> A Windows named pipe seems to be more like a UNIX-side "UNIX domain
> socket" than a UNIX side "named pipe".
> 
>> For linux it's simpler using os.mkfifo:
> 
> Not really. For Linux (and of course other UNIXen) you really want a
> UNIX domain socket, not a a name pipe (as from mkfifo).
> 
> The reason is that a socket (and a Windows pipe, from my limited
> understanding) creates a new distinct connection when you open it. (The
> other end has to accept that connection, at least in UNIX).
> 
-----------------
> The problem with a UNIX pipe is that every client (your command line
> control script) _share_ the same pipe - if two scripts un at once there
> will be a failure. If you contrive some locking scheme then you can
> share a named pipe in UNIX because only once client will use the pipe at
> a time.
> 

This is not completely true, in fact requests can be queued as they 
would be with sockets and it is their real job. The most important 
difference is that sockets are a limited resource on a system.

> Just something to keep in mind.
> 
> Cheers,
> Cameron Simpson <cs at cskk.id.au>
> 


From bob at mellowood.ca  Thu Dec 31 17:46:16 2020
From: bob at mellowood.ca (Bob van der Poel)
Date: Thu, 31 Dec 2020 15:46:16 -0700
Subject: Funny error message
Message-ID: <CA+HdcZhB3mP9RYjUHDgKOvEuEVQP-3xQA7fNbPrE=J+xeX+Avw@mail.gmail.com>

When I run python from the command line and generate an error I get the
following:

Python 3.8.5 (default, Jul 28 2020, 12:59:40)
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> z
/home/bob/.local/lib/python3.8/site-packages/requests/__init__.py:89:
RequestsDependencyWarning: urllib3 (1.24.3) or chardet (4.0.0) doesn't
match a supported version!
  warnings.warn("urllib3 ({}) or chardet ({}) doesn't match a supported "
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'z' is not defined

I understand "z in not defined" ... but what's with the warnings?

-- 

**** Listen to my FREE CD at http://www.mellowood.ca/music/cedars ****
Bob van der Poel ** Wynndel, British Columbia, CANADA **
EMAIL: bob at mellowood.ca
WWW:   http://www.mellowood.ca

From nospam at please.ty  Thu Dec 31 18:45:52 2020
From: nospam at please.ty (jak)
Date: Fri, 1 Jan 2021 00:45:52 +0100
Subject: Control stript which is runing in background.
References: <rsl0gh$qsv$1@gioia.aioe.org> <X+5GFnXOavnABHTu@cskk.homeip.net>
 <mailman.585.1609451043.7193.python-list@python.org>
 <rslmmd$it0$1@gioia.aioe.org>
Message-ID: <rslnrd$v7h$1@gioia.aioe.org>

... but this won't be the problem the OP may encounter if its intention 
is to create a script to command another one that is running. It will be 
sufficient to limit the write permissions to the pipe file to himself 
... perhaps protecting the pipe file inside a directory with stickibits set.

From 2QdxY4RzWzUUiLuE at potatochowder.com  Thu Dec 31 18:58:24 2020
From: 2QdxY4RzWzUUiLuE at potatochowder.com (2QdxY4RzWzUUiLuE at potatochowder.com)
Date: Thu, 31 Dec 2020 17:58:24 -0600
Subject: Control stript which is runing in background.
In-Reply-To: <rslnrd$v7h$1@gioia.aioe.org>
References: <rsl0gh$qsv$1@gioia.aioe.org> <X+5GFnXOavnABHTu@cskk.homeip.net>
 <mailman.585.1609451043.7193.python-list@python.org>
 <rslmmd$it0$1@gioia.aioe.org> <rslnrd$v7h$1@gioia.aioe.org>
Message-ID: <X+5loMM/DyFF0mKT@scrozzle>

On 2021-01-01 at 00:45:52 +0100,
Regarding "Re: Control stript which is runing in background.,"
jak <nospam at please.ty> wrote:

> ... but this won't be the problem the OP may encounter if its intention is
> to create a script to command another one that is running. It will be
> sufficient to limit the write permissions to the pipe file to himself ...
> perhaps protecting the pipe file inside a directory with stickibits set.

Most of the time, I have several shells open, often with their own
background jobs running.  Limiting write permission on the pipe to "me"
wouldn't prevent concurrent access.

From nospam at please.ty  Thu Dec 31 19:21:48 2020
From: nospam at please.ty (jak)
Date: Fri, 1 Jan 2021 01:21:48 +0100
Subject: Control stript which is runing in background.
References: <rsl0gh$qsv$1@gioia.aioe.org> <X+5GFnXOavnABHTu@cskk.homeip.net>
 <mailman.585.1609451043.7193.python-list@python.org>
 <rslmmd$it0$1@gioia.aioe.org> <rslnrd$v7h$1@gioia.aioe.org>
 <X+5loMM/DyFF0mKT@scrozzle>
 <mailman.587.1609459114.7193.python-list@python.org>
Message-ID: <rslpup$1nek$1@gioia.aioe.org>

Il 01/01/2021 00:58, 2QdxY4RzWzUUiLuE at potatochowder.com ha scritto:
> Most of the time, I have several shells open, often with their own
> background jobs running.  Limiting write permission on the pipe to "me"
> wouldn't prevent concurrent access.

This is true but there would be no difference if this happened through a 
socket.

From cs at cskk.id.au  Thu Dec 31 19:43:43 2020
From: cs at cskk.id.au (Cameron Simpson)
Date: Fri, 1 Jan 2021 11:43:43 +1100
Subject: Control stript which is runing in background.
In-Reply-To: <rslpup$1nek$1@gioia.aioe.org>
References: <rslpup$1nek$1@gioia.aioe.org>
Message-ID: <X+5wPxxrDjWAkjyQ@cskk.homeip.net>

On 01Jan2021 01:21, jak <nospam at please.ty> wrote:
>Il 01/01/2021 00:58, 2QdxY4RzWzUUiLuE at potatochowder.com ha scritto:
>>Most of the time, I have several shells open, often with their own
>>background jobs running.  Limiting write permission on the pipe to "me"
>>wouldn't prevent concurrent access.
>
>This is true but there would be no difference if this happened through 
>a socket.

Accessing a socket makes a distinct separate data connection - other 
openers do not conflict with it. That's the critical difference between 
a socket and a pipe in terms of functionality, and why sockets have a 
connect/accept step.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From nospam at please.ty  Thu Dec 31 21:43:43 2020
From: nospam at please.ty (jak)
Date: Fri, 1 Jan 2021 03:43:43 +0100
Subject: Control stript which is runing in background.
References: <rslpup$1nek$1@gioia.aioe.org> <X+5wPxxrDjWAkjyQ@cskk.homeip.net>
 <mailman.588.1609461828.7193.python-list@python.org>
Message-ID: <rsm28r$al0$1@gioia.aioe.org>

Il 01/01/2021 01:43, Cameron Simpson ha scritto:
> On 01Jan2021 01:21, jak <nospam at please.ty> wrote:
>> Il 01/01/2021 00:58, 2QdxY4RzWzUUiLuE at potatochowder.com ha scritto:
>>> Most of the time, I have several shells open, often with their own
>>> background jobs running.  Limiting write permission on the pipe to "me"
>>> wouldn't prevent concurrent access.
>>
>> This is true but there would be no difference if this happened through
>> a socket.
> 
> Accessing a socket makes a distinct separate data connection - other
> openers do not conflict with it. That's the critical difference between
> a socket and a pipe in terms of functionality, and why sockets have a
> connect/accept step.
> 
> Cheers,
> Cameron Simpson <cs at cskk.id.au>
> 

Maybe the fact that I'm not English and I don't know the language well
doesn't allow me to express myself clearly. Try it one more time:
The OP would like to give some command to a script that is running. How?
With a script that sends commands to it. One of the ways, as mentioned,
is by using a mini socket server. Given the needs of the OP and the fact
that sockets are a limited resource in a system, I took the liberty of
proposing a simple alternative: using a named pipe, also because, IMO,
sockets, in this case, are an overkill. with a few lines of code in a
thread in the running script they can allow it to receive commands:
#-----------------
import os, errno

fnpipe = 'cmdpipe'

try:
     os.mkfifo(fnpipe)
except OSError as e:
     if e.errno != errno.EEXIST:
         raise
while True:
     with open(fnpipe, 'rt', 1) as fifo:
         for line in fifo:
             print(line, ends='')
#-----------------

Running the command:

$ cat bible.txt > cmdpipe & cat bible.txt > cmdpipe & cat bible.txt > 
cmdpipe

the three texts do not mix. IMO, the OP should be enough. after that, I
know that a pipe is more like a queue than a soket and in this case a
socket, IMO, is wasted.

greetings, hoping to have been clearer than before.

From 2QdxY4RzWzUUiLuE at potatochowder.com  Thu Dec 31 22:14:41 2020
From: 2QdxY4RzWzUUiLuE at potatochowder.com (2QdxY4RzWzUUiLuE at potatochowder.com)
Date: Thu, 31 Dec 2020 21:14:41 -0600
Subject: Control stript which is runing in background.
In-Reply-To: <rsm28r$al0$1@gioia.aioe.org>
References: <rslpup$1nek$1@gioia.aioe.org> <X+5wPxxrDjWAkjyQ@cskk.homeip.net>
 <mailman.588.1609461828.7193.python-list@python.org>
 <rsm28r$al0$1@gioia.aioe.org>
Message-ID: <X+6Toa3apy918iUD@scrozzle>

On 2021-01-01 at 03:43:43 +0100,
Regarding "Re: Control stript which is runing in background.,"
jak <nospam at please.ty> wrote:

> Il 01/01/2021 01:43, Cameron Simpson ha scritto:
> > On 01Jan2021 01:21, jak <nospam at please.ty> wrote:
> > > Il 01/01/2021 00:58, 2QdxY4RzWzUUiLuE at potatochowder.com ha scritto:
> > > > Most of the time, I have several shells open, often with their own
> > > > background jobs running.  Limiting write permission on the pipe to "me"
> > > > wouldn't prevent concurrent access.
> > > 
> > > This is true but there would be no difference if this happened through
> > > a socket.
> > 
> > Accessing a socket makes a distinct separate data connection - other
> > openers do not conflict with it. That's the critical difference between
> > a socket and a pipe in terms of functionality, and why sockets have a
> > connect/accept step.
> > 
> > Cheers,
> > Cameron Simpson <cs at cskk.id.au>
> > 
> 
> Maybe the fact that I'm not English and I don't know the language well
> doesn't allow me to express myself clearly. Try it one more time:
> The OP would like to give some command to a script that is running. How?
> With a script that sends commands to it. One of the ways, as mentioned,
> is by using a mini socket server. Given the needs of the OP and the fact
> that sockets are a limited resource in a system, I took the liberty of
> proposing a simple alternative: using a named pipe, also because, IMO,
> sockets, in this case, are an overkill. with a few lines of code in a
> thread in the running script they can allow it to receive commands:
> #-----------------
> import os, errno
> 
> fnpipe = 'cmdpipe'
> 
> try:
>     os.mkfifo(fnpipe)
> except OSError as e:
>     if e.errno != errno.EEXIST:
>         raise
> while True:
>     with open(fnpipe, 'rt', 1) as fifo:
>         for line in fifo:
>             print(line, ends='')
> #-----------------
> 
> Running the command:
> 
> $ cat bible.txt > cmdpipe & cat bible.txt > cmdpipe & cat bible.txt >
> cmdpipe
> 
> the three texts do not mix. IMO, the OP should be enough. after that, I
> know that a pipe is more like a queue than a soket and in this case a
> socket, IMO, is wasted.

Only the OP knows for sure.  :-)   Does the server send data back to the
client that made the request?  Are the requests (and the responses, if
any) small enough to be sent/received atomically?  *If* the answers are
no and yes, then you're right, a named pipe would be good enough.  If
not, then a socket *might* be better.  Until the OP clarifies, we can't
tell.

> greetings, hoping to have been clearer than before.

I think you were clear enough before, but you may not have considered
things the OP did not specify.  One of the hardest parts of software
development is understanding and specifying the actual problem to be
solved.  I've never done that in a second language (I'm nowhere near
fluent in anything other than English); I can only imagine the extra
layers of complexity.

From PythonList at DancesWithMice.info  Thu Dec 31 23:25:24 2020
From: PythonList at DancesWithMice.info (DL Neil)
Date: Fri, 1 Jan 2021 17:25:24 +1300
Subject: Funny error message
In-Reply-To: <CA+HdcZhB3mP9RYjUHDgKOvEuEVQP-3xQA7fNbPrE=J+xeX+Avw@mail.gmail.com>
References: <CA+HdcZhB3mP9RYjUHDgKOvEuEVQP-3xQA7fNbPrE=J+xeX+Avw@mail.gmail.com>
Message-ID: <b7f01ecd-cd56-4445-9651-4c690b5b8192@DancesWithMice.info>

On 1/1/21 11:46 AM, Bob van der Poel wrote:
> When I run python from the command line and generate an error I get the
> following:
> 
> Python 3.8.5 (default, Jul 28 2020, 12:59:40)
> [GCC 9.3.0] on linux
> Type "help", "copyright", "credits" or "license" for more information.
>>>> z
> /home/bob/.local/lib/python3.8/site-packages/requests/__init__.py:89:
> RequestsDependencyWarning: urllib3 (1.24.3) or chardet (4.0.0) doesn't
> match a supported version!
>   warnings.warn("urllib3 ({}) or chardet ({}) doesn't match a supported "
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> NameError: name 'z' is not defined
> 
> I understand "z in not defined" ... but what's with the warnings?


The implication is that there is a version-mismatch between Python 3.8
and whichever urllib3 and chardet libraries currently installed.

Recommend updating the system, container, or venv: either Python, pip3
of the two and/or requests or html-parser [as appropriate to the
installed libraries - see below], or both/all.


System here runs as-expected:

dn $ ... python
Python 3.9.1 (default, Dec  8 2020, 00:00:00)
[GCC 10.2.1 20201125 (Red Hat 10.2.1-9)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> z
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'z' is not defined
>>> import chardet
>>> import urllib3
>>> exit()
dn $ ... pip show chardet urllib3
Name: chardet
Version: 3.0.4
Summary: Universal encoding detector for Python 2 and 3
Home-page: https://github.com/chardet/chardet
Author: Mark Pilgrim
Author-email: mark at diveintomark.org
License: LGPL
Location: /usr/lib/python3.9/site-packages
Requires:
Required-by: html5-parser, requests
---
Name: urllib3
Version: 1.25.8
Summary: HTTP library with thread-safe connection pooling, file post,
and more.
Home-page: https://urllib3.readthedocs.io/
Author: Andrey Petrov
Author-email: andrey.petrov at shazow.net
License: MIT
Location: /usr/lib/python3.9/site-packages
Requires:
Required-by: requests

-- 
Regards =dn