[gentoo-portage-dev] Re: Dynamic USE dependencies

[Martin Vaeth]

Rich Freeman <rich0@g.o> wrote:
> On Sun, Apr 5, 2015 at 11:47 AM, Martin Vaeth <martin@×××××.de> wrote:
>> One suggestion around this problem would be to use different
>> directories for these two types of use-flags, say
>> "package.use" and "package.use.needed".
>
> I still think we need a better long-term solution, but the workaround
> is simpler than that.
>
> I try to keep files in directories for package.keywords and
> package.use.  One starts with a z and is a dumping ground for
> auto-whatever.

So you use package.use/z instead of package.use.needed
as in my suggestion. (In fact, I do currently a similar
thing, only that I use a file named zzz_autounmask,
because this is even later in the alphabet).

I think it would be more transparent to the user if
really a dedicated directory/file would be used and not
some which "by accident" is the last in the alphabet.

Anyway, this is a minor issue.
The main problem is how to cleanup this directory/file
(no matter how it is called).

Currently, the only way to do this, is to remove this
file and to hope that portage can recreate it.
Unfortunately, quite often portage is not able to do this.
The problem is at least NP hard, so probably any
backtracking value just is too low.

If portage would use the old values as a hint, how
conflicts might possibly be resolved, perhaps this
algorithm might be improved.

> However, I think a cleaner solution would be better...

++

My suggestion is something in between - less invasive
(and, in particular, less time consuming)
than your suggestion to recalculate the USE-settings
with every emerge, but more automatic than the current state.

With my suggestion the USE-settings have to be recalculated
only if a special command is used (or - as currently -
if resolving is not possible without changing USE-flags).

Probably other approaches are possible, too.