Archive:PackagingDrafts/Python3

Packaging Python modules for Python 3

I hope to add a parallel-installable Python 3 stack to Fedora 13.

See the feature page: https://fedoraproject.org/wiki/Features/Python3F13 and also this thread: https://www.redhat.com/archives/fedora-devel-list/2009-October/msg00054.html

This requires us to come up with a sane way to package Python 3 modules, and this requires us to generalize our python packaging rules to support more than one python runtime.

The existing Python packaging guidelines are here: Packaging/Python

Runtimes

There will be multiple python runtimes, one for each supported major/minor release combination.

Each runtime corresponds to a binary of the form /usr/bin/python$MAJOR.$MINOR

One of these python runtimes is the "system runtime". It can be identified by the destination of the symlink /usr/bin/python

The output of "rpm -q --provides" of each runtime rpm MUST contain a line of the form:

 Provides: python-abi-$MAJOR-$MINOR-$MAGIC

For example, a python-2.7 runtime rpm with ABI 62171 should have this output:

 Provides: python-abi-2.7-62171

and another with ABI 62181 should have this output:

 Provides: python-abi-2.7-62181

(this is a change from current guidelines, to allow for different runtimes to be installable in parallel, and allowing for multiple magic numbers)

Naming

(to be written)

Layout

Proposed rule: All files with an extension of .py/.pyo/.pyc MUST be either

• within a runtime package, and below /usr/lib/python$MAJOR-$MINOR for that runtime, or
• for a specific runtime package, and below /usr/lib/python$MAJOR-$MINOR/site-packages for that runtime, or
• for the system python runtime.

For example, python code for the 3.1 runtime needs to be below /usr/lib/python3.1/site-packages

.pyo/.pyc files

Compiled .pyo/.pyc files embed a magic number, indicating which python version they are for; python libraries have a corresponding magic number.

Proposed rule: All .pyo/.pyc files below /usr/lib/python$MAJOR.$MINOR MUST have a magic number corresponding to that for /usr/bin/python$MAJOR.$MINOR

Thus e.g. /usr/lib/python2.6/site-packages/libxml2.pyc must have the same magic number as that of /usr/bin/python2.6

Similarly, /usr/lib/python3.1/site-packages/libxml2.pyc must have the same magic number as that of /usr/bin/python3.1

TODO: write an rpmlint test for this. See initial work here: https://www.zarb.org/pipermail/rpmlint-discuss/2009-October/000775.html and here: http://dmalcolm.fedorapeople.org/rpmlint/add-tests-for-python-bytecode-files.patch