[Fedora-packaging] Python 3 compatibility update to Python guidelines

[David Malcolm]

On Sat, 2009-10-17 at 13:33 +0300, Ville Skyttä wrote:
> https://fedoraproject.org/wiki/Packaging:Python
> 
> %{!?python_sitelib: %global python_sitelib %(%{__python} -c "from 
> distutils.sysconfig import get_python_lib; print get_python_lib()")}
> 
> %{!?python_sitearch: %global python_sitearch %(%{__python} -c "from 
> distutils.sysconfig import get_python_lib; print get_python_lib(1)")}
> 
> 
> These no longer work with Python 3 due to "print" changes.  They should be 
> replaced with something like these that work with both Python 2 and 3 (already 
> done in spectemplate-python.spec in rpmdevtools git):
> 
> %{!?python_sitelib: %global python_sitelib %(%{__python} -c "from 
> distutils.sysconfig import *; import sys; 
> sys.stdout.write(get_python_lib())")}
> 
> %{!?python_sitearch: %global python_sitearch %(%{__python} -c "from 
> distutils.sysconfig import *; import sys; 
> sys.stdout.write(get_python_lib(1))")}

At first glance, yes, the change you suggest does generalize those
fragments of python code so they work with both python 2 and python 3
(it removes the trailing newline implicitly generated by "print", but
AIUI that's getting discarded in the macro handling)

However, I think it's going to be a long time until it's sane to make
%{__python} be python 3 rather than python 2.  I'm hoping we will have
parallel-installable python 2 and python 3 stacks [1], with separate
packages, probably separate srpms, so perhaps we need alternative
formulations where we define python3_sitelib and python3_sitearch?  Not
sure yet.

Your proposed change does ease migration, so a cautious "+1" from me.

Dave
[1] https://fedoraproject.org/wiki/Features/Python3F13