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

[Dirkjan Ochtman <djc@gentoo.org>]

On Thu, Nov 15, 2012 at 10:44 PM, Michał Górny <mgorny@gentoo.org> wrote:
> Of course, a MIP would not be allowed to depend on a SIP.

How big of a problem would this be?

> 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.

> - 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.

> - 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.

Cheers,

Dirkjan