[Python-Dev] Distutils and Distribute roadmap (and some words on Virtualenv, Pip)

[Tarek Ziadé]

On Thu, Oct 8, 2009 at 11:42 AM, David Cournapeau <cournape at gmail.com> wrote:
> On Thu, Oct 8, 2009 at 5:31 PM, Tarek Ziadé <ziade.tarek at gmail.com> wrote:
>
>> = Virtualenv and the multiple version support in Distribute =
>>
>> (I am not saying "We" here because this part was not discussed yet
>> with everyone)
>>
>> Virtualenv allows you to create an isolated environment to install
>> some distribution without polluting the
>> main site-packages, a bit like a user site-packages.
>>
>> My opinion is that this tool exists only because Python doesn't
>> support the installation of multiple versions for the same
>> distributions.
>
> I am really worried about this, because it may encourage people to use
> multiple versions as a bandaid to maintaining backward compatibility.
> At least with virtual-env, the problem is restricted to the user.
>
> Generalized multiple, side by side installation  has been tried in
> many different contexts, and I have never seen a single one working
> and not bringing more problems that it solved. One core problem being
> the exponential number of combination (package A depends on B and C, B
> depends on one version of D, C on another version of D). Being able to
> install *some* libraries in multiple versions is OK, but generalizing
> is very dangerous IMHO.

The goal here is to be able to have a *single* instance of "Foo 1.2" on your
system, managed by the admin sys. that can be shared and used for
several python
apps. And yes, I don't expect to have so many different versions of
many distributions
on a system, but just to provide a mechanism to allow it.

But that's just an idea we had with some people, and it still requires
a lot of work and brainstroming (even if the prototype kinda work)

I should've mentioned that I've added it at the end of the roadmap
because I had the feeling that something has to be done to reunite
zc.buildout, virtualenv and Python one day.

But consider this as the topic for the "fun sprint" we would have at
Pycon, after we will have issued other points. If you are interested
in this particular topic, I propose that we continue this discussion
on distutils-SIG.

Regards
Tarek