Multiple concurrent versions of Python

[Aurelien Bompard]

Hello y'all,

During the event "Solutions Linux" in Paris, I met a Zope developper who had
very good arguments on how Fedora could be improved to support more Python
applications (and Zope in particular).

Since Fedora is rather python-oriented, and we're considering Zope for our
CMS, I think we should consider this. I maintain the Zope & Plone packages
in Extras, and I must say it's complicated, because Zope requires specific
versions of python (not the latest) and Plone requires specific versions of
Zope :
- Latest Plone requires Zope 2.8.5
(http://plone.org/products/plone/releases/2.1.2)
- Latest Zope is 2.9, which works with python 2.4.2, but zope 2.8.5 is
unsupported on python 2.4, it requires python 2.3.4
(http://www.zope.org/Products/Zope/2.8.5/Zope-2_8_5-released)

Since Fedora only ships python 2.4, there is no way for the Zope & Plone
packages to run on a supported python.

The solution discussed with the Zope dev would be to ship python 2.3.5.
There is a way to ship both versions, using the "alternatives" system (like
sendmail and postfix). The symlink would be on /usr/bin/python
and /usr/bin/python2.

The only problem is with python modules and python applications which
install files in /usr/lib/python2.4
 - python modules should be compiled for both versions of python ex:
python-imaging and python23-imaging
 - python applications installing files in /usr/lib/python2.4 should not
have #!/usr/bin/python in the shebang, but the required version :
#!/usr/bin/python2.4 and the package should require python24. The current
python rpm could Provide python24.

This is the way Debian does it, for example. And it works :)

Since installing concurrent versions of python is technically possible, do
you think this could be done in Fedora (of course, I'm not talking FC5
here) ?

What do you think ? Any corner cases ?

Regards,
Aurélien
-- 
http://aurelien.bompard.org  ~~~~  Jabber : abompard at jabber.fr
"Programming today is a race between software engineers striving to build
bigger and better idiot-proof programs, and the Universe trying to produce
bigger and better idiots. So far, the Universe is winning." -- Rich Cook