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

Greg Ward gward@python.net
Tue, 3 Jul 2001 09:51:23 -0400

On 03 July 2001, Gregor Hoffleit said:
> So let me paraphrase: Provided the maintainer of the Debian Python
> package would do a good job and keep the package always up-to-date,
> would you think there's a real world need for concurrent Python versions
> on the same system ?

Speaking as someone who uses Python day-to-day and occasionally worries
about compatibility across Python versions: yes, it would be really nice
if Python better supported multiple versions installed at the same time.
lib/python1.5, lib/python2.0, and lib/python2.1 just don't cut it: I
remember running 1.5.1, 1.5.2, and alpha/beta versions of 1.6
simultaneously.  I had to install each to a separate prefix, which was
ugly but workable.  It would be nice if Python (and, yes, the Distutils
now) had better native support for multiple simultaneous versions.

Speaking as the main perpetrator of the Distutils: AAUUGGHGHHHH!!!!
NOOOOO!!!  Please, don't make me look at this stuff AGAIN!!!!

But seriously: I think I once attempted to convince Guido that a
revamped organization of the library directories would be a good idea,
and that the Distutils would be a good way to introduce that scheme.
Obviously, I didn't convince him, so we still have the same system.  The
one glimmer of good news is that the Distutils "install" command is
insanely flexible; if you can manage to wrap your head around the 17,000
levels of indirection, it should be a simple matter of changing a few
hard-coded dictionaries (there are two for Unix, and one each for
Windows and Mac OS) to introduce a completely new installation scheme.
I probably had some expectation that someday this discussion would open
up again.

BTW, I'm skeptical about keeping .py and .pyc code in a
non-Python-version-specific directory (ie. site-python).  Debian's
bytecode-recompilation at installation time scheme sounds cool, but the
desire/need to have multiple Python versions available kind of nixes it.

Oh yeah, another thing I vaguely recall from the pre-Distutils-0.1 era:
Guido doesn't (didn't?) like site-python and wanted to deprecate it.
Perhaps the above paragraph explains why.

Greg Ward - Linux geek                                  gward@python.net
Drive defensively -- buy a tank.