Re: [gentoo-dev] PROFILE-IUSE-INJECTION implicit things (Was: PMS EAPI 3 more or less ready)

[Tiziano Müller]

Am Montag, den 20.04.2009, 13:41 +0100 schrieb Ciaran McCreesh:
> Let's see if we can keep to one thread per item here.
>
> On Mon, 20 Apr 2009 07:14:00 +0200
> Tiziano Müller <dev-zero@g.o> wrote:
> > > * PROFILE-IUSE-INJECTION
> > yes, but *_IMPLICIT has to be discussed.
>
> There are a few suggested use cases for these:
>
> * Avoiding the need for developers to have to explicitly list ARCH in
>   IUSE. Without implicits, ARCH will be empty and USE won't contain the
>   arch flag name unless IUSE explicitly lists it. Some developers would
>   rather not list arch flags explicitly.

> * Ditto for things like USERLAND.
>
> * People want to be able to carry on using flags like 'build' that
>   wouldn't otherwise work.

Why should those USE flags be different than others?

The user should anyway not check the ebuild if he wants to figure out
what USE flags a package supports but rather consult the PM's output
(because USE flags may also come from an eclass), so the argument of
hiding that info from the user is nil (and with USE_EXPAND_HIDDEN
userland and arch USE flags get hidden anyway as pointed out below).
So, with _IMPLICIT we would have some USE flags which don't have to be
added while some will have to be added and in the end devs who use those
vars only occasionally will always have to consult the specs.
Instead I'd prefer to be implicit about it: the use flags you use have
to be given in IUSE. One simple rule to remember...


>
> And a few related points that people might otherwise miss:
>
> * Listing something in IUSE does not have to mean it will show up in
>   package manager output. There are special HIDDEN variables for those.
>
> * Without this whole stricter USE mess, [use(+)] dependencies are
>   rather crippled. You can't do [linguas_en(+)] against any existing
>   EAPI, for example.
>