[Python-ideas] Add a site.cfg to keep a persistent list of paths

[Ron Adam]

On 10/20/2010 08:38 AM, Nick Coghlan wrote:
> On Wed, Oct 20, 2010 at 7:57 PM, Paul Moore<p.f.moore at gmail.com>  wrote:
>> On 19 October 2010 22:26, Tarek Ziadé<ziade.tarek at gmail.com>  wrote:
>>> There's one feature I want to add in distutils2: the develop command
>>> setuptools provides. Basically it adds a "link" file into
>>> site-packages, and does some magic at startup to load the path that is
>>> contained in the link file. The use case is to be able to have a
>>> project added in the python path without installing it.
>>
>> Can you explain the requirement in more detail? I don't use the
>> setuptools develop command, so I don't have the background, but it
>> seems to me that what you're proposing can be done simply by adding
>> the relevant directory to PYTHONPATH. That's all I ever do when
>> developing (but my needs are pretty simple, so there may well be
>> subtle problems with that approach).
>
> A different idea along these lines that I've been pondering is an
> actual -p path option for the interpreter command line, that allowed a
> sequence of directories to be provided that would be prepended to
> PYTHONPATH (and hence included in sys.path).
>
> So if you're wanting to test two different versions of a module (from
> a parent directory containing the two versions in separate
> subdirectories):
>
> python -p versionA run_tests.py
> python -p versionB run_tests.py
>
> For more permanent additions to sys.path, PYTHONPATH (possibly in
> conjunction with virtualenv) is reasonable answer. Zipfile and
> directory execution covers execution of more complex applications
> containing multiple files as if they were simple scripts.
>
> The main piece I see missing from the puzzle is the ability to easily
> switch back and forth between multiple versions of a support package
> or library without mucking with persistent state like the environment
> variables or the filesystem.

Yes, I don't like changing the system wide environment variables and file 
system options. It's too easy to break other things that depend on them.

How about adding the ability to use a .pth file from the current program 
directory?

Ron