[Python-Dev] versioned .so files for Python 3.2

[Scott Dial]

On 6/25/2010 2:58 PM, Brett Cannon wrote:
> I assume you are talking about PEP 3147. You're right that the PEP was
> for pyc files and that's it. No one is talking about rewriting the
> PEP.

Yes, I am making reference to PEP 3147. I make reference to that PEP
because this change is of the same order of magnitude as the .pyc
change, and we asked for a PEP for that, and if this .so stuff is an
extension of that thought process, then it should either be reflected by
that PEP or a new PEP.

> The motivation Barry is using is an overarching one of distros
> wanting to use a single directory install location for all installed
> Python versions. That led to PEP 3147 and now this work.

It's unclear to me that that is the correct motivation, which you are
divining. As I understand it, the motivation to be to *simplify
installation* for distros, which may or may not be achieved by using a
single directory. In the case of pure-python packages, a single
directory is an obvious win. In the case of mixed-python packages, I
remain to be persuaded there is any improvement achieved.

> This is meant to be used by distros in a programmatic fashion, so my
> response is "so what?" Their package management system is going to
> maintain the directory, not a person.

Then why is the status quo unacceptable? I have already explained how
this will still require programmatic steps of at least the same
difficulty as the status quo requires, so why should we change anything?

I am skeptical that this is a simple programmatic problem either: take
any random package on PyPI and tell me whether or not it has a .so file
that must be compiled. If such a .so file exists, then this package must
be special-cased and compiled for each version of Python on the system
(or will ever be on the system?). Such a package yields an arbitrary
number of .so files due to the number of version of Python on the
machine, and I can't imagine how it is simpler to manage all of those
files than it is to manage multiple site-packages.

> You're conflating what is being discussed with PEP 3147. That PEP is
> independent of this. PEP 3147 just empowered this work to be relevant.

Without a PEP (be it PEP 3147 or some other), what is the justification
for doing this? The burden should be on "you" to explain why this is a
good idea and not just a clever idea.

-- 
Scott Dial
scott at scottdial.com
scodial at cs.indiana.edu