[Distutils] setuptools special case Pyrex and break Cython

[Phillip J. Eby]

At 09:24 PM 9/4/2007 +0200, Stefan Behnel wrote:

>Stefan Behnel wrote:
> > Phillip J. Eby wrote:
> >> The key design question I ask for setuptools features is "who gets the
> >> pain?", since nearly all design decisions will cause *somebody* pain.
> >> Ideally, I want that pain to go to somebody who's in a position to do
> >> something that improves things for everybody in the long term.
> >>
> >> In this case, the only additional pain is for the developers of new
> >> tools that process .pyx files (such as yourself).
> >
> > Wrong. I cannot fix this as a developer of Cython - at least not without
> > providing a fake build_ext.py in a fake Pyrex package, which would make
> > installing Pyrex and Cython on the same machine near impossible and which
> > would break every tool that requires Pyrex instead on Cython.
>
>Ok, admittedly, I could change sys.path to point it to an internal directory
>of the installed Cython distribution, so that setuptools would be tricked into
>succeeding with a fake Pyrex import - but how ugly is that?

Isn't Cython a *replacement* for Pyrex?  If not, then why does it use 
.pyx files?  If it is, then why is installing both a problem?  (It's 
not like you can't switch back and forth between them.)


>The right way of fixing this is definitely in setuptools, and the quick fix is
>to extend the test import of Pyrex.Distutils.build_ext.build_ext with an
>additional test for Cython.Distutils.build_ext.build_ext in the failure case -
>if you don't feel like taking the cleaner step of checking for a "build_ext"
>replacement...

Perhaps you'd care to produce a patch to implement that "cleaner 
step"?  It's not at all obvious to me how to do that without 
introducing instability that would be unsuitable for an 0.6cN release.