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

[David Cournapeau]

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.

David