[Python-Dev] In-Python virtualisation and packaging (original) (raw)

Vinay Sajip vinay_sajip at yahoo.co.uk
Mon Jun 13 14:50:01 CEST 2011

Nick Coghlan <ncoghlan gmail.com> writes:

Given that it is desirable for tools like virtualenv to support old versions of Python on new versions of operating systems, it seems to me that there is an inherent element of their feature set that makes including the whole tool questionable.

You're right in terms of the current Python ecosystem and 3.x adoption, because of course this approach requires support from Python itself in terms of its site.py code. However, virtual environments have a utility beyond supporting older Pythons on newer OSes, since another common use case is having different library environments sandboxed from each other on different projects, even if all those projects are using Python 3.3+. The virtualenv module does an intricate bootstrapping dance which needs to accommodate each successive Python version, so there's maintenance overhead that way, too. Carl Meyer, being a pip and virtualenv maintainer, will probably have useful views on this.

OTOH, it may make sense to have a baseline tool provided innately, but provide the appropriate third party hooks to allow alternative tools to evolve independently of the stdlib.

Yes - I'm thinking that what I've proposed is the baseline tool, and the question is about what the virtualisation API needs to look like to allow third-party tools to progress independently of the stdlib but in an interoperable way (a bit like packaging, I suppose).

How well does the regression test suite cope when run inside such a virtualised environment?

https://gist.github.com/1022705

325 tests OK. 5 tests failed: test_email test_importlib test_lib2to3 test_packaging test_sysconfig

test_importlib might be broken because I accidentally committed some changes to marshal.c while working on #12291.

test_packaging fails because of #12313. test_email fails for a similar reason - Makefile.pre.in is missing test_email in LIBSUBDIRS.

test_sysconfig is probably failing because of changes I made, and I'm not sure of test_lib2to3. I will investigate!

Regards,

Vinay Sajip

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