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

Michael Foord fuzzyman at voidspace.org.uk
Thu Oct 8 18:30:00 CEST 2009

Toshio Kuratomi wrote:
> On Thu, Oct 08, 2009 at 02:52:24PM +0200, Simon Cross wrote:
>>  On Thu, Oct 8, 2009 at 10:31 AM, Tarek Ziadé <ziade.tarek at gmail.com> wrote:
>>> = Virtualenv and the multiple version support in Distribute =
>> ...
>>> My opinion is that this tool exists only because Python doesn't
>>> support the installation of multiple versions for the same
>>> distributions.
> Let's actually look at these reasons:
>> This is not at all how I use virtualenv. For me virtualenv is a
>> sandbox so that I don't have to become root whenever I need to install
>> a Python package for testing purposes
> This is needing to install multiple versions and use the newly installed
> version for testing.

Not really - it is wanting to install a single version of a library that 
you don't want to install into your 'main' (whether that be user or 
system) Python install. It is sandboxing and orthogonal to multiple 

>> and to allow me to hop between
>> sets of installed Python packages while developing on multiple Python
>> projects.
> This is the ability to install multiple versions and specify different
> versions for different projects you're working on.

No, it is working on multiple projects that have *different* 
dependencies and being able to work in an environment that *only* has 
direct dependencies installed - again sandboxed from your main Python 

The fact that virtualenv allows you to have multiple different versions 
of the same library installed in the different environments you create 
is completely separate from the motivation that causes many people to 
use it.

What virtualenv *doesn't* do (I believe) is allow you to have multiple 
versions of libraries installed within a single environment and switch 
between them (at least it doesn't offer anything beyond what setuptools 
or pip provides).

>> I also use it as a sandbox for build bots so that multiple
>> bots on the same machine can each build their own projects with just
>> the known dependencies installed.
> This is the only use in the list that is virtualenv specific.  The rest are
> cases of needing to install multiple versions on the system.
> -Toshio
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