[gentoo-python] python-any-r1 and MERGE_TYPE

[Michał Górny]

Hello,

After adding python_gen_any_dep to solve issues with dependencies of
python-any-r1 packages, there's yet another thing that needs some of
our attention.

Most of python-any-r1 ebuilds use Python during build-time only. I'm
not aware of a single python-any-r1 ebuild that would use Python during
pkg_* functions. This means that a typical python-any-r1 ebuild would
need to:

  pkg_setup() {
    [[ ${MERGE_TYPE} != binary ]] && python-any-r1_pkg_setup
  }

As you can guess, only a few ebuilds actually do that, and it's not
really friendly to repeat that over and over again.

While having this snippet missing usually doesn't cause much bad, it
can be quite hurtful to binary packages in the future. Most
importantly, when an ebuild uses uncommon version of Python during
build time, the binary package will fail to install --
python-any-r1_pkg_setup will bail out being unable to find supported
Python.

Therefore, I think it would be beneficial to add the MERGE_TYPE check
inside pkg_setup. In case someone needs Python during binary package
install, we can (likely in the future):

1. add a variable to disable the MERGE_TYPE check,

2. add a new function that does the actual Python setup and make
the default pkg_setup() a common-case wrapper for it.

What are your thoughts?

-- 
Best regards,
Michał Górny