Mailman 3 May 2018 - docs

[issue26701] Documentation for int constructor mentions __int__ but not __trunc__
by Robert Smallshire 10 May '18

10 May '18

New submission from Robert Smallshire: The documentation for the int(x) constructor explains that if possible, it delegates to x.__int__(). The documentation does not explain that there is a fallback to x.__trunc__() if x.__int__() is not available. The only mention of __trunc__ in the Python documentation is in the entry for math.trunc; the documentation for the numbers module does not describe the underlying special methods. Given that all Real numbers are required to implement __trunc__ but only Integral subclasses are required to implement __int__ this could be important to implementers of other Real types, although in practice I imagine that most Real types will implement __int__ as float does. ---------- assignee: docs@python components: Documentation messages: 262941 nosy: Robert Smallshire2, docs@python priority: normal severity: normal status: open title: Documentation for int constructor mentions __int__ but not __trunc__ type: enhancement versions: Python 3.5 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue26701> _______________________________________

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[issue32288] Inconsistent behavior with slice assignment?
by Massimiliano Culpo 10 May '18

10 May '18

New submission from Massimiliano Culpo <massimiliano.culpo(a)googlemail.com>: I am not really sure if what I am reporting is to be considered a bug in the interpreter (slice built-in), a lack in documentation or if it is just me not finding the proper references (in which case feel free to close this and sorry for the noise). Anyhow, while trying to code a class that mimics built-in lists, I noticed a few seemingly inconsistent behaviors in the use of slices to set items. This can be reduced down to this very simple example: ``` Python 3.6.2 (default, Jul 29 2017, 00:00:00) [GCC 4.8.4] on linux # 1. Slice has start and stop, step is defaulted to None >>> a = [1, 2, 3, 4] >>> a[1:3] = [11, 22, 33, 44] >>> a [1, 11, 22, 33, 44, 4] # 2. Same as above setting explicitly step == 1 >>> a = [1, 2, 3, 4] >>> a[1:3:1] = [11, 22, 33, 44] >>> a [1, 11, 22, 33, 44, 4] # 3. Trying to do the same thing with step == -1 # (I naively expected either [1, 44, 33, 22, 11, 4] or 2. to fail like 3.) >>> a = [1, 2, 3, 4] >>> a[3:1:-1] = [11, 22, 33, 44] Traceback (most recent call last): File "<input>", line 1, in <module> ValueError: attempt to assign sequence of size 4 to extended slice of size 2 ``` Now, the first issue: I tried to search what an "extended slice" is exactly, but found nothing in the docs. What is written here https://docs.python.org/3/library/functions.html#slice seems to suggest that an "extended slice" is a slice where `step is not None`, but then I would expect case 2. to behave the same as case 3. So to me it appears as either lack of documentation on the behavior, or a bug in 2. Second issue: in the same page in the docs it's written > slice objects are also generated when extended indexing syntax is used. For example: a[start:stop:step] or a[start:stop, i] I wasn't aware of the second syntax, and tried to use it: ``` >>> a = [1, 2, 3, 4] >>> a[1:3:1] [2, 3] >>> a[1:3, 1] Traceback (most recent call last): File "<input>", line 1, in <module> TypeError: list indices must be integers or slices, not tuple ``` I guess that's not the result one would expect... Third issue: slightly related, but here https://docs.python.org/3/library/stdtypes.html#mutable-sequence-types I see that the documentation of `insert` reads: > inserts x into s at the index given by i (same as s[i:i] = [x]) and from the interpreter: ``` help(list.insert) Help on method_descriptor: insert(...) L.insert(index, object) -- insert object before index ``` Here the fact is that `insert` really behaves like `s[i:i] = [x]`, but in my understanding it doesn't keep the promise to `insert object before index`. ``` # "Out of bounds" on the right >>> a = [1, 2, 3, 4] >>> a.insert(101, 11) >>> a [1, 2, 3, 4, 11] # "Out of bounds" on the left >>> a.insert(-101, 11) >>> a [11, 1, 2, 3, 4] ``` I don't know honestly if docs are not clear here, or if it is just me, but I didn't expect this behavior and thought it was worth reporting. Let me know if you need more information. ---------- assignee: docs@python components: Documentation, Interpreter Core messages: 308120 nosy: Massimiliano Culpo, docs@python priority: normal severity: normal status: open title: Inconsistent behavior with slice assignment? type: behavior versions: Python 2.7, Python 3.4, Python 3.5, Python 3.6 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue32288> _______________________________________

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issue
by 14JHarvey＠stanwell.org 09 May '18

09 May '18

I am using Python 3.3 the main code is shown in uploaded pic "Capture1". The part in the code that is apparently broken is the Postcode1 variable. As shown in pic "Capture2", after I have converted the entire string to a list (each letter seperated), a c is shown at the front of the list, however, this only occurs sometimes (most of the time as sometimes this does not happen) as shown in "Capture3", when the code loops back round this never occurs. The rest of the pics (4 and onwards) displays the rest of the code, I have also attatched the code. Thanks Disclaimer This email and any attachments are confidential. Unless you are the intended recipient, you may not use, copy or disclose either the message or any information contained within the message. If you are not the intended recipient, you should delete this email and notify the sender immediately. Any views or opinions expressed in this email are those of the sender only and not that of Stanwell School unless otherwise stated. Stanwell School emails and any attachments have not been encrypted; they may therefore be liable to compromise. Please also note that it is your responsibility to scan emails and any attachments for viruses. Stanwell School<http://www.stanwell.org>

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[issue13525] Tutorial: Example of Source Code Encoding triggers error
by Nicolas Goutte 09 May '18

09 May '18

New submission from Nicolas Goutte <nicolas.goutte(a)extragroup.de>: Current Behaviour The tutorial of Python 3.2.x has an example to set an encoding in a source file: http://docs.python.org/py3k/tutorial/interpreter.html#source-code-encoding It explains to set the following line at the start of the source code: # -*- coding: cp-1252 -*- However when done exactly so, Python raises the following exception: SyntaxError: encoding problem: with BOM The problem seems to be that Python knows Windows codepage 1252 as windows-1252 (its IANA charset name, see http://www.iana.org/assignments/charset-reg/windows-1252 ) or alternatively as cp1252 (without dash) but not as cp-1252 (with dash). As this is an example in the tutorial is particularly problematic, as users might not understand how to do it correctly. This is still the case in the tutorial of Python 3.3 alpha: http://docs.python.org/dev/tutorial/interpreter.html#source-code-encoding Expected Behaviour The tutorial should give a correct example, for example with: # -*- coding: windows-1252 -*- Alternatively a totally other example as for Python 2.7 would be nice too: http://docs.python.org/tutorial/interpreter.html#source-code-encoding Notes: I have tested this with following Python implementations: - Python 3.2.1 (openSUSE 12.1) on Linux - Python 3.2.2 on Windows 7 SP1 64 Bits - Python 3.2.2 on MacOS 10.5.8 (Always on the command line; I have not tested in IDLE.) ---------- assignee: docs@python components: Documentation files: cp_1252broken.py messages: 148798 nosy: docs@python, nicolasg priority: normal severity: normal status: open title: Tutorial: Example of Source Code Encoding triggers error versions: Python 3.2 Added file: http://bugs.python.org/file23840/cp_1252broken.py _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue13525> _______________________________________

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[issue6673] Uncaught comprehension SyntaxError eats up all memory
by Serhiy Storchaka 09 May '18

09 May '18

Serhiy Storchaka <storchaka+cpython(a)gmail.com> added the comment: "yield" in comprehensions is deprecated in 3.7: ../issue6673.py:22: DeprecationWarning: 'yield' inside list comprehension target.send([ (yield) for i in range(chunk_size) ]) and an error in 3.8: File "../issue6673.py", line 22 target.send([ (yield) for i in range(chunk_size) ]) ^ SyntaxError: 'yield' inside list comprehension ---------- nosy: +serhiy.storchaka resolution: -> duplicate stage: needs patch -> resolved status: open -> closed superseder: -> yield expression inside generator expression does nothing _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue6673> _______________________________________

1 0

frozenset.copy() does not create a copy
by Mihail Temelkov 08 May '18

08 May '18

Tried it in Python 2.7 and found that it just creates an alias to the original set.

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add explain about where to set use_builtin_types when use customTransport
by peng yu 08 May '18

08 May '18

I'm using xmlrpc, and I'm using a custom Transport, follow the "21.26.8. Example of Client Usage" section of below document: https://docs.python.org/3/library/xmlrpc.client.html I found if I use a custom transport, set use_builtin_types parameter to xmlrpc.client.ServerProxy will have no effect. After read the source code, I found if I use a custom transport, I should set the use_builtin_types parameter in the transport. I think it is better to describe this behavior in the document. best regards.

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[issue33426] Behavior of os.path.join does not match documentation
by Michael Klatt 05 May '18

05 May '18

New submission from Michael Klatt <michael.d.klatt(a)gmail.com>: The behavior of os.path.join() regarding path separators does not match the documentation. This affects Python 3.6, and goes back to at least Python 2.7. >From the documenation: "The return value is the concatenation of path and any members of *paths with exactly one directory separator (os.sep) following each non-empty part except the last, meaning that the result will only end in a separator if the last part is empty." To me, this means that join will remove extraneous separators from the path, and that the only way to produce a trailing separator is to use join "" as the final path segment. I expect `os.path.join("/abc//", "def/")` to produce the string "/abc/def" based on the documentation, but what it actually produces is "abc//def/". ---------- assignee: docs@python components: Documentation, Library (Lib) messages: 316184 nosy: Michael Klatt, docs@python priority: normal severity: normal status: open title: Behavior of os.path.join does not match documentation type: behavior versions: Python 2.7, Python 3.4, Python 3.5, Python 3.6 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue33426> _______________________________________

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[issue32362] multiprocessing.connection.Connection misdocumented as multiprocessing.Connection
by Mark 05 May '18

05 May '18

New submission from Mark <markamery(a)btinternet.com>: https://docs.python.org/3/library/multiprocessing.html#multiprocessing.Conn… purports to document the multiprocessing.Connection class. There's no such thing: Python 3.6.1 (v3.6.1:69c0db5050, Mar 21 2017, 01:21:04) [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import multiprocessing >>> multiprocessing.Connection Traceback (most recent call last): File "<stdin>", line 1, in <module> AttributeError: module 'multiprocessing' has no attribute 'Connection' I think it should be multiprocessing.connection.Connection? ---------- assignee: docs@python components: Documentation messages: 308539 nosy: Amery, docs@python priority: normal severity: normal status: open title: multiprocessing.connection.Connection misdocumented as multiprocessing.Connection versions: Python 2.7, Python 3.4, Python 3.5, Python 3.6, Python 3.7, Python 3.8 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue32362> _______________________________________

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[issue33431] Change description about doc in programming, faq.
by lvhuiyang 05 May '18

05 May '18

Change by lvhuiyang <ilvhuiyang(a)gmail.com>: ---------- keywords: +patch pull_requests: +6398 stage: -> patch review _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue33431> _______________________________________

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