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

David Cournapeau cournape at gmail.com
Thu Oct 8 11:42:28 CEST 2009

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

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