[gentoo-dev] Re: [rfc] Sane defaults for USE_PYTHON, patch to python eclass

[Arfrever Frehtes Taifersar Arahesis]

2010-12-04 01:23:41 Sebastian Pipping napisał(a):
> Current situation
> =================
> Without specifying USE_PYTHON in /etc/make.conf ebuilds based on the
> python eclass will install packages for no more ABIs than the two active
> versions on the 2.x and 3.x lines.  To give an example: with Python 2.6,
> 2.7 and 3.1 installed and 2.7 set as the active 2.x Python version I
> would get files installed for python 2.7 and 3.1, but not 2.6.
>
> Is that a sane default?  Especially when a new slot of Python arrives at
> the Gentoo tree, you run into situations with two slots of Python 2.x
> installed.  To have packages functioning with both, you would need a
> custom USE_PYTHON line like USE_PYTHON="2.6 2.7" - otherwise one of
> these slots' Python will be very limited.
>
> This problem is made worse by the fact that USE_PYTHON has almost no
> documentation.  This bug shows well, that the current behavior is a
> surprising troublemaker:
>
> https://bugs.gentoo.org/show_bug.cgi?id=347153
>
>
> Proposed new situation
> ======================
> If I have a version of Python installed, it should be usable well.
> So USE_PYTHON is derived from the list of all available Python slots.

Please don't change current algorithm.
- Average users need packages built with support for at most 1 version of Python 2 and at most
  1 version of Python 3.
- Only people, who want to explicitly test given modules/scripts with multiple Python versions,
  would need dependencies built with support for more Python versions.
- You might break something outside of python.eclass.

There is a plan (and patches) to introduce usage of USE flags for selection of requested 
Python versions. It will be available when a future EAPI supports dots in names of USE flags.

-- 
Arfrever Frehtes Taifersar Arahesis