Multiple concurrent versions of Python

[Jeremy Katz]

On Wed, 2006-02-22 at 11:05 +0100, Aurelien Bompard wrote:
> 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 :

I really think that this needs to be resolved by making those apps work
better with more current versions of python.  By that argument, what if
someone wanted to build an app which was only "supported" on a 2.4
kernel -- would you argue that we should also add the infrastructure for
supporting a variety of incompatible kernel versions?

> 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

This would hugely increase the burden on testing python modules across a
variety of python versions.  And the end result would be that you end up
with most things not supported on the non-primary python.

>  - 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.

So now to upgrade Core from one version of python to another, I have to
touch every python app, even if they don't install files into
python_sitelib?  And not just a rebuild either, I have to make actual
changes to the included scripts.  Where currently, if I just rebuild
with a "correct" python package, it will DTRT.

Jeremy