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

Toshio Kuratomi a.badger at gmail.com
Thu Oct 8 20:52:53 CEST 2009

On Thu, Oct 08, 2009 at 05:30:00PM +0100, Michael Foord wrote:

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 versions. What I'm replying to is specifically the need to: "become root whenever I need to install a Python package for testing purposes" That doesn't require sandboxing at all. Can you use sandboxing to do this? Yes. But that is separate to being able to install a non-system version of a library and be able to test it.

My quoting of that phrase could have been better -- I missed the reference to sandboxing since it is in a separate clause of the sentence from what I was responding to.

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 environment. No. Here what is written is: "allow me to hop between sets of installed Python packages while developing on multiple Python projects."

There's nothing about only having direct dependencies installed. That's a separate requirement than what was written.

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. Precisely! We see 100% eye-to-eye here. My reply is just trying to say that the ideas of

are completely satisfiable without sandboxing. Virtualenv is a sandboxing tool. It can be used to perform these tasks. But it isn't necessary. Having sandboxing is an additional feature on top of the base requirements to perform the task.

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). Yep. Which makes virtualenv unsuitable for certain other problem spaces where sandboxing is inappropriate.

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