[Tutor] Cmd Advice

[Walter Prins]

Hi all,

Below is an *earlier* (note the date) private response by myself that
at the time accidentally didn't get sent to the list and only to Dave
(as he privately replied to me only and not to the list.) Given that
the thread on the list has resumed,  I thought I'd forward this to the
thread for completeness sake as otherwise a bit of context might be
lost.

Regards,

Walter


---------- Forwarded message ----------
From: Walter Prins <wprins at gmail.com>
Date: 8 February 2012 01:29
Subject: Re: [Tutor] Cmd Advice
To: Dave Hanson <dave at hansonforensics.co.uk>


HI Dave,


On 7 February 2012 16:55, Dave Hanson <dave at hansonforensics.co.uk> wrote:
>
> I tried what you said, many attempts result in this message:
>
>>
>> C:\Documents and Settings\dhanson2\Desktop>"C:\Python27\python.exe" "C:\t.py"
>>
>> C:\Python27\python.exe: can't open file 'C:\t.py': [Errno 2] No such file or directory
>
>
> I've tried moving t.py around but still no joy?
>
> Here is what I put in my bat file with and without the quotes:
>
>>
>> "C:\Python27\python.exe" "C:\t.py" %1 %2 %3 %4 %5 %6 %7 %8 %9
>
>

The error message implies that the program "t.py" is in the root of
your C:\ drive?  I'd have thought this would not be the case -- you
need to give the correct path to the "t.py" file for Python to load
it. (And as an aside, you need to quote paths if theycontains spaces,
otherwise the command prompt will interpret the first part up to a
space in the path as the path/command and the remainder of the path as
a command line argument!  (One subtlety of command lines...)  The
"Documents and Settings" folder on Windows XP was therefore very
unfortunately chosen since the spaces causes endless problems with
people not realising this and trying to use files located inside
Documents and Settings.  You'll notice on Windows 7 Microsoft has
wisely (at last) decided to shorten and remove spaces as much as
possible from paths to avoid gotchas with people forgetting to quote
paths, and similarly Python itself does not uses spaces in any of its
folder names.  But I digress.

Anyway, I've had a quick further look at this program and got it
working the way you want on my machine.  The precise steps I followed
was:
1.) Install Mercurial for Windows (to be able to checkout the source).
 I got it here: http://tortoisehg.bitbucket.org/download/index.html
2.) Retrieved the source code.  On my machine I opened a command prompt, and:
cd "C:\Users\walterp\Documents\Python"
hg clone https://bitbucket.org/sjl/t

This creates a folder called "t" inside of my Python source folder.
Adjust folders as required for your machine and/or where you keep your
Python source.

3) Create a batch file called "t.bat" in
"C:\Users\walterp\Documents\Python\t", so the full filename is
"C:\Users\walterp\Documents\Python\t\t.bat", containing these lines:

@echo off
c:
cd C:\Users\walterp\Documents\Python\t
c:\python27\python.exe "C:\Users\walterp\Documents\Python\t\t.py" %1
%2 %3 %4 %5 %6 %7 %8 %9

The effect of these commands is to stop the command interpreter from
displaying the commands issues by the batch file (which is unwanted
here) via the "@echo off" line, and then setting up the environment
prior to running the t.py program such that it will always run having
the "current working folder" be the same folder that the t.py program
is located in.

This is important since the t.py program currently assumes that it
will always be run from the same starting location, which is not the
case if you go and put the program on the command line search path so
that you can use it from any other working folder.  (Without this, if
you run the program from another location, then the t.py program will
create a new task list in the new location -- basically the t.py
command will create and manage a task list in whatever folder you
happen to be in, so in order to ensure it always updates the same task
list, the lines above therefore ensures it always effectively runs
from the same place, regardless of where the batch file t.bat might
have been run from, thereby effectively ensuring it to always uses the
same task list file.)

Also, note that in order to in fact use the t.bat file from any other
folder, you'll have to add the bat files location to you system (or
user) PATH variable.  Do you know how to do this, and are you allowed
to do so, or are you blocked by your IT policies?  If so you should
also be able to do this via e.g. another batch file, perhaps the same
one you use to circumvent the cmd.exe blocks on your system, by simply
adding it to the PATH variable there, e.g. a line like this ought to
do it:
PATH=%PATH%;C:\Users\walterp\Documents\Python\t

Lastly a minor observation:  I note this source code includes a
setup.py script.  This implies you can install t.py into your Python
environment such that an .exe file will be created for it (really copy
of the t.py file and the python interpreter [I think, or a launcher of
some sort] combined) in the Python\Scripts folder.  Some Python
distributions (e.g. Activestate IIRC) puts this folder onto the system
Path thereby making "system wide" installed Python packages/commands
(where appropriate) instantly usable from the command prompt, others
(e.g. standard Python on Windows) do not and leaves this step for you
to complete.  Anyway, I've obviously not gone the route of installin
via setup.py, since installing this program in this way will make it
difficult/impossible for you to tinker/edit the program easily, and
I'm assuming you want to actually be able to edit the program (and
possibly submit patches back to the author?) while using it etc.  So,
for this to be possible you actually need the t.py to "run from
source" and don't want to embedded in your Python environment, which
is what not using setup.py and doing the above effectively enables you
to do easily. (Aside: when I noticed the program isn't
location/working directory independent I immediately thought this
might be a useful patch/enhancement to make -- make it get the folder
location of itself and use that for the location of the tasks list
etc.)

Let me know if you have further problems.

Walter