Re: [gentoo-dev] Re: Remember to specify SLOT when adding subslot operator to dependencies

[Ciaran McCreesh]

On Tue, 6 Aug 2013 15:31:14 -0400
Alexis Ballier <aballier@g.o> wrote:
> Well, ok, but this doesn't relate to what I was writing. Subslot, or
> slot emulators or whatever, in their current usage with :=
> dependencies, are not fine grained enough for some use cases. Those
> cause regressions if used improperly.

There is no regression. Previously, packages sometimes broke when doing
an upgrade. Now, packages do not break when doing an upgrade.

> > You just make the ebuilds install different bits. In effect you
> > emulate a simple subset of how parts would do it.
>
> Which needs patching to be done properly... unless you are suggesting
> to build it twice and throw away whats not needed just to workaround
> subslots limitations.

It's up to the relevant developers to decide how much work they're
willing to put in to save some users a bit of CPU time.

> > > Or you can do parts/subpackages or subslot dictionaries to express
> > > that.
> >
> > Realistically, parts will never get implemented in Portage. Subslot
> > dictionaries might be, if anyone ever figures out what they're
> > supposed to be, but they're a heavy price for package developers to
> > pay. The question under discussion is whether it's a price worth
> > paying to avoid an occasional unnecessary rebuild. Since users do
> > far more unnecessary rebuilds for other reasons anyway, and
> > reducing CPU usage has never been a goal for Gentoo, I'm not
> > convinced it's worth caring about.
>
> Meanwhile, there's preserve-libs :)

Which causes breakage.

> Your argumentation is basically 'Other parts are doing it wrong so
> it's ok to add some more to it'... We're back a dozen emails back,
> aren't we?

It's not adding more to it. It's avoiding eliminating a tiny portion of
it. Even if you subscribe to the notion that unnecessary rebuilds are a
relevant problem, there's no point in caring about the occasional
unnecessary rebuild due to overly strict dependencies when most
unnecessary rebuilds are caused by something else entirely.

> It was meant as an example and has nothing to do with dependency
> resolution. The above exercise is something extreme but that we have
> to solve; preserve-libs has proven to be correct enough. You have yet
> to show a correct, in your sense, solution.

The correct solution is heavy slotting. And I'd hardly consider
"intermittently introduces invisible security holes and causes
unbootable systems" to be "correct enough"...

-- 
Ciaran McCreesh