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

[Barry Warsaw]

On Jun 24, 2010, at 10:48 AM, Brett Cannon wrote:

>While the idea is fine with me since I won't have any of my
>directories cluttered with multiple .so files, I would still want to
>add some moniker showing that the version number represents the
>interpreter and not the .so file. If I read "foo.3.2.so", that naively
>seems to mean to mean the foo module's 3.2 release is what is in
>installed, not that it's built for CPython 3.2. So even though it
>might be redundant, I would still want the VM name added.

I have a new version of my patch that steals the "magic tag" idea from PEP
3147.  Note that it does not use the *actual* same piece of information to
compose the file name, but for now it does match the pyc tag string.

E.g.

% find . -name \*.so
./build/lib.linux-x86_64-3.2/math.cpython-32.so
./build/lib.linux-x86_64-3.2/select.cpython-32.so
./build/lib.linux-x86_64-3.2/_struct.cpython-32.so
...

Further, by default, ./configure doesn't add this tag so that you would have
to build Python with:

% SOABI=cpython-32 ./configure

to get anything between the module name and the extension.  I could of course
make this a configure switch instead, and could default it to some other magic
string instead of the empty string.

>Adding the VM name also doesn't make extension modules the exclusive
>domain of CPython either. If some other VM decides to make their own
>.so files that are not binary compatible then we should not preclude
>that as this solution it is nothing more than it makes a string
>comparison have to look at 7 more characters.
>
>-Brett
>
>P.S.: I wish we could drop use of the 'module.so' variant at the same
>time, for consistency sake and to cut out a stat call, but I know that
>is asking too much.

I think you're right that with the $SOABI trick above, you wouldn't get the
name collisions Guido recalls, and you could get rid of module.so.  OTOH, as I
am currently only targeting Linux, it seems like the module.so stat is wasted
anyway on that platform.

-Barry
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