Re: [gentoo-dev] GLEP 29 (USE Flag Grouping) with -@GROUP goodness

[Ciaran McCreesh]

On Sun, 24 Oct 2004 18:31:19 +0200 Maurice van der Pot
<griffon26@g.o> wrote:
| The problem with -something seems to be two-fold:
| 1) it's hard to realize the consequence of double negations

True.

| 2) with -@GROUP1 and @GROUP2 where both groups share a use flag
|    it is order dependent whether or not the common use flag will
|    be in the end result

That's already an issue, though... If you USE="foo -foo", and then have
a per-package "foo" USE flag set up, we're already dealing with
order-sensitive material.

| Whether a use flag is specifically turned off for a group or it is
| just not present in the group should make no difference for the
| meaning of GROUP. The same holds for -@GROUP. In other words, -use and
| -@GROUP should only be used in the definition of a group to filter
| flags out.
| 
| Assume MYGNOME="@GNOME -gtk", then USE="... -@MYGNOME ..." should
| *not* be equivalent to USE="... -@GNOME gtk ...", instead it should
| not influence the state of gtk at all.

Interesting idea. This then brings us back to one of the original
objections, which was that there should be some way to turn off flags
from within a group. Only way to do that would be to introduce yet
another modifier, which is inconsistent with the rest of portage and
will confuse the heck out of anyone who hasn't studied set theory...

| I would specify it like this:
| 
| 	KDE $X kde qt -gtk -gnome
| 	GNOME $X gtk gtk2 gnome -kde -qt
| 
| 	USE="@KDE @GNOME"
| 
| That would result in:
| 	USE="X kde qt gtk gtk2 gnome"
| 
| Exactly what the user wants.

Hm. Although, I don't think "I want KDE" should imply "I don't want
GNOME" anyway...

-- 
Ciaran McCreesh : Gentoo Developer (Vim, Fluxbox, Sparc, Mips)
Mail            : ciaranm at gentoo.org
Web             : http://dev.gentoo.org/~ciaranm