Re: Draft: Macros to tell what Python versions to package for

[Miro Hrončok]

On 2.3.2018 11:25, Pavel Raiskup wrote:
> On Friday, March 2, 2018 10:36:36 AM CET Miro Hrončok wrote:
> > I've prepared a draft for Python packaging that introduces some new
> > macros that should ease packaging for Fedoras, EPELs and even potential
> > new RHELs, when it comes to python stacks.
> >
> > I don't do much ifs in specfiles and prefer to leverage git branches for
> > this, so I don't know what bothers you most. The proposal with example
> > spec file is at:
> >
> > https://fedoraproject.org/wiki/User:Churchyard/Packaging:PythonMustMayMacros
> > [..snip..]
> > Could you please provide feedback? Ask questions?
>
> What's the real usecase for *_must?

This tells you that according to the guidelines for given distro, if 
upstream supports this python version, you MUST package for it.
Some packages might want to only package their Python library for the 
stacks where it's required.
> Why the py2_must is not defined for
> epel7 and epel6?

Because there is no such guideline. It is completely OK to package for 
python3 only on EPELs.
> I always only needed to see whether (a) python2 runtime is available, (b)
> python3 is available.  So more readable and understandable approach (to
> me) would be to have only the %pyX_may (or %py3_available).  But I'm
> probably not experienced enough, so I'm only curious :-).

For that, yes. here may == available. We can discuss the naming if it 
sounds weird.
> E.g. last time (argparse-manpage) I went with:
>
> %if 0%{?fedora}
>      %bcond_without python2
>      %bcond_without python3
>    %else
>      %if 0%{?rhel} > 7
>        %bcond_with    python2
>        %bcond_without python3
>      %else
>        %bcond_without python2
>        %bcond_with    python3
>      %endif
>    %endif
>
> Which allows me to do things like:
>
> %if %{with python2}
>      ....
>    %endif
>
> Or:
>
> BuildRequires: %{?with_python3:foo} %{?with_python2:bar}
>
> .. and which brings the convenient --with{,out}-python{2,3} options for
> custom re-builds.  Could we have something similar in the draft, too?

We can definitively make those with statemetns, however we cannot make 
it with_python2 and with_python3, because we might destroy current 
specfiles with that. So we would need to have:

%if %{with python2_must}
      ....
    %endif

Or:

BuildRequires: %{?with_python3_may:foo} %{?with_python2_must:bar}

And specifying those on the command line would be rather unreadable. 
What does --with-python2-may even mean?

You can always define your with_python2 based on values of py2_may, 
py2_must and fedora version.