Re: [gentoo-dev] Re: use flags -> use options

["Marijn Schouten (hkBst)" <hkBst@gentoo.org>]

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Marius Mauch wrote:
> So what you want is a USE_EXPAND version that only allows one value
> per variable. That wouldn't be terribly difficult to do.

I extremely dislike that characterization. What I want is use flags with more
than two possible values. I see no reason to warp that to fit USE_EXPAND.
There may even be uses where this could be used in combination with USE_EXPAND.

> As for your idea (ignoring implementation issues), I'd expect that
> sooner or later people will request multivalue functionality as well,
> so we'd have the same situation there.

Right, current use flags are "2 options, pick 1", I am requesting "n options,
pick 1" and you're saying "n options, pick m, (m<n)" might be useful too.

But "n options, pick m, (m<n)" reduces to n times "2 options, pick 1" (you
decide for each possible value whether to include it or not). This is exactly
why our "2 options, pick 1" system works so well most of the time.

> Also in the given example, how
> would the user/package manager actually know what values were
> valid/available for "impl"?

That is a good question. If all possible options need to be specified a syntax
should be developed for that. How about:

IUSE="+default_on_flag normalflag
multiwayflag={option1,option2,+default_option} -default_off_flag",

or

IUSE="+default_on_flag normalflag multiwayflag={option1 option2
+default_option} -default_off_flag",

or

IUSE="+default_on_flag normalflag multiwayflag=(option1 option2
+default_option) -default_off_flag".

In use.[local.]desc the multiwayflag description should explain what each
alternative means.

Marijn

- --
Marijn Schouten (hkBst), Gentoo Lisp project
<http://www.gentoo.org/proj/en/lisp/>, #gentoo-lisp on FreeNode
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