Re: [gentoo-dev] New eclass for Python

[Alexandre Rostovtsev <tetromino@gentoo.org>]

On Tue, 2012-02-28 at 22:13 +0100, Krzysztof Pawlik wrote:
> Hello,
> 
> After some work during weekend on Python packages I've decided to start a
> rewrite of Python/distutils eclass for installing Python packages. My main goal
> was simplicity and functionality similar to ruby-ng.eclass (thanks Ruby team for
> your great work!). Python team members already contributed comments and
> suggestions and helped me to make the eclass better, thank you!
> 
> Highlights:
>  - *SIMPLE*next
>  - uses PYTHON_TARGETS use-expand (no more python-updater, whoooo!)
>  - EAPI4 required, uses REQUIRED_USE
>  - <400 lines of code including documentation
>  - should work for >95% of packages (my educated guess)
>  - did I mention it's *SIMPLE*?
>  - easy to maintain & read so it's also easy to use
> 
> Important thing: I'm not aiming at having 100% functionality of current
> python.eclass+distutils.eclass in the new one, I think that simplicity is more
> important that supporting every possible, obscure case that's out there.
> 
> I'm attaching the eclass itself and two ebuilds using it, code is also available
> in my overlay at http://git.overlays.gentoo.org/gitweb/?p=dev/nelchael.git;a=summary
> 
> If there are no objections then during the weekend (March 3, 4) I will add this
> to portage (after finishing remaining TODO items, PyPy requires 4G of RAM(!!)).

The proposed eclass omits three features from python.eclass which are
heavily used in the gnome stack.

First, it does not set EPYTHON, which is a problem for the many packages
whose build systems execute /usr/bin/python and assume that it's a
generic python2 or the same version of python2.x for which the package
is being built.

Second, there doesn't seem to be any support for packages that do not
install in python's site-packages and do not allow multiple python ABIs.
If I have, for example, a package that installs python modules
in /usr/lib/appname or /usr/share/appname, how can I specify that
PYTHON_TARGETS="python2.6" or "python2.7" or "python3.2" is allowed, but
something like PYTHON_TARGETS="python2.7 python3.2" is not?

Third, python-distutils-ng_doscript() installs only one file at a time
(no built-in support for multiple files at a time or for recursing
through a directory tree), installs it only in /usr/bin (a package might
want it in e.g. /usr/libexec or /usr/share/appname/scripts), and always
creates scriptname-IMPLEMENTATION (polluting tab-completion in /usr/bin
for the common case of programs that do not support multiple python
ABIs). As a result, it is far less useful than python.eclass's
python_convert_shebangs().

-Alexandre.