Re: [gentoo-python] Re: Package supporting single implementation only -- auxiliary variable solution

[Michał Górny]

On Mon, 19 Nov 2012 10:57:52 +0100
Dirkjan Ochtman <djc@g.o> wrote:

> On Thu, Nov 15, 2012 at 10:44 PM, Michał Górny <mgorny@g.o> wrote:
> > Of course, a MIP would not be allowed to depend on a SIP.
>
> How big of a problem would this be?

None at all. Just stating the obvious fact, in case anyone wanted
to try doing that or point out that my solution is not well though
out :).

> > To sum it up quickly, the aux variable solution:
> >
> > Advantages:
> > - painless for most of our users,
> > - explicit, transparent,
> > - simple and matching SIP->SIP and SIP->MIP deps.
> >
> > Disadvantages:
> > - a bit redundant,
>
> Given the requirement for enabling multiple implementation in
> PYTHON_TARGETS, which I feel strongly about, there has to be a choice
> which one of the implementations will be target for SINGLE_TARGET
> packages. Adding a variable for that, therefore, doesn't seem
> redundant.

Well, some people could argue that if they set PYTHON_TARGETS
to a single value (like python3.2), they need to set an auxiliary
variable as well. But that's the lesser evil, I think.

> > - does not solve the issue for py3-only SIP packages,
>
> I guess this might become a problem in the future. Once we have both
> py2-only SIP packages and py3-only SIP packages, we have a bit of a
> problem. Maybe we should think more about that.

Let's grep the tree then (and a few random overlays I'm using)...

I have used the following command:

$ find -name '*.ebuild' -exec grep -L SUPPORT_PYTHON_ABIS {} + \
  | xargs grep PYTHON_DEPEND

I have counted 1372 ebuilds not supporting multiple Python
implementations, in 648 packages.

Of those ebuilds:
- 4 ebuilds (1 pkg) support both Python 2 & 3:
  - media-gfx/hugin;
- 8 ebuilds (3 pkgs) require Python 3:
  - sys-power/upower with USE=test,
  - media-gfx/blender (3.2+),
  - net-irc/znc with USE=python.

Considering that's ~0.6% of all packages, I'd say we could just be lazy
and use package.use for them.

> > - may require explicit action when changing PYTHON_TARGETS.
>
> Yeah, I don't see a problem with this. In particular, it seems
> unlikely that many people will setup their system to exclude the
> default SINGLE_TARGET impl (2.7) from their TARGETS.

-- 
Best regards,
Michał Górny