[Python-Dev] PEP 250, site-python, site-packages

Guido van Rossum guido@digicool.com
Tue, 03 Jul 2001 10:38:07 -0400

> > What about when you want to have multiple python versions, like python
> > 1.5.2, 2.0.1, 2.1.1 and 2.2-CVS-snapshot ? :-)
> You've hit the forbidden question ;-)
> Seriously, does anybody (besides the Python developers) feel a need to
> have multiple Python versions on the same system ?

I've had enough requests over the years for this, so it is indeed
supported, and I believe there is a need.  Quite often people have
important programs that for some minor reason don't work on a newer
version yet and they can't find the person or the time to fix it.

Python's standard installation makes this possible.  You can have only
one "python" but you can request a specific version by appending the
"major dot minor" part of the version number, e.g. python1.5,
python2.0, python2.1, python2.2.  "python" is a hard link to one of
these.  You can't (easily) have multiple version with the same
major.minor, but that should never be needed.  I've heard though that
some Linux distributors break this versioning scheme in favor of their

> If there's a real world need for this, then, yes, we had to come up with
> a completely different setup. I guess this setup might involve symlink
> farms (urghh).

Ugh maybe, but it's the only thing that scales.

--Guido van Rossum (home page: http://www.python.org/~guido/)