Re: [gentoo-dev] Re: useflag policies

[Rich Freeman]

On Tue, Aug 11, 2015 at 3:13 PM, Gregory Woodbury <redwolfe@×××××.com> wrote:
> Is a possible solution something like an eselect module to indicate
> the preferred
> interface kit? It could default to any package that is available with
> a sequential
> set of preferred order.
> Then ebuild would consult the eselect module, and users who care can
> select the kit they want, and users who don't care/know get the default.

That still neglects the case where a user just wanted to say "use the
best version of qt for any particular package," which I'd argue is
probably the most common use case.  It may not make sense to have one
global preference system-wide, and managing it per-package is painful.
It really does make sense to leave it up to the maintainer, while
still letting people either turn off qt entirely if they'd prefer to
do so, or override the default implementation when they really want
to.

There is always requiring any package that supports qt to enable
either qt4 or qt5 by default, so the typical user who wants qt does
nothing, the typical user who doesn't want qt sets USE="-qt4 -qt5",
and then anybody who wants to override things per-package can do so.
That is simple to define in ebuilds, and you can set REQUIRED_USE to
prevent them both from being set.  It just means having qt support by
default all over the tree and forcing people who don't want it to
explicitly turn it off.  That is simple to do at least, but not really
in keeping with the general spirit of the base profile being a minimal
one.  And it would still be difficult to do anything at the profile
level if it were appropriate to do so.

-- 
Rich