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

[Ian Bicking]

On Wed, Oct 20, 2010 at 6:35 PM, Floris Bruynooghe <flub at devork.be> wrote:

>
> On 20 October 2010 15:27, Tarek Ziadé <ziade.tarek at gmail.com> wrote:
> > On Wed, Oct 20, 2010 at 4:00 PM, Paul Moore <p.f.moore at gmail.com> wrote:
>
> >> But I'm probably not seeing the real issues here.
> >>
> >> All I would say is, don't let the needs of more unusual configurations
> >> over-complicate basic usage.
> >
> > The trouble is: adding in PYTHONPATH the root of the source of your
> > project can be different from what it would be once installed in
> > Python.   Now the question is: if 90% of the projects out there would
> > work by adding the root, then this is might be overkill. I am afraid
> > it's way less though...
>
> I've read your and Ian's responses and still don't understand what
> setup.py develop brings to the party which can't be done with simple
> PYTHONPATH.  Excuse me if I also completely misunderstand what develop
> does but it sounds like it's going to add an in-development version of
> a project on a users's sys.path (at the front?) until it's undone
> again somehow (is there a "setup.py undevelop"?).


pip uninstall would unlink it (pip install -e calls setup.py develop as
well).  setup.py develop is persistent unlike PYTHONPATH.


>  This just seems
> dangerous to me since it will affect all python programs run by that
> user.
>

Hence virtualenv, which solves your other concerns.


> If I understand correctly this whole "develop" dance is for when you
> have two inter-depended packages in development at the same time.  If
> manually setting PYTHONPATH correctly in this situation is too
> complicated then my feeling is there's nothing wrong with some sort of
> helper which manipulates PYTHONPATH for you, something like spaw a new
> shell and set the environment in that correctly.  But placing things
> in files makes this permanent for the user and just seems the wrong
> way to go to me.
>
> Again, apologies if I understand the problem wrongly.  But I too am
> worried about too many complexities and "magic".  One of my main
> issues with setuptools is that it tries to handle my python
> environment (sys.path) outside of normally expected python mechanisms
> by modifying various custom files.  I would hate to see distutils2
> repeat this.
>

Note if you use pip, it uses setuptools in a way where only setup.py develop
uses .pth files, and otherwise the path is similar to how it is with
distutils alone (except with that extra metadata, as Doug mentions).

-- 
Ian Bicking  |  http://blog.ianbicking.org
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