Re: [gentoo-dev] "Lazy" use flags?

[Daniel Campbell]

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On 02/09/2016 07:08 PM, Gordon Pettey wrote:
>
> On Tue, Feb 9, 2016 at 7:19 AM, Kent Fredric
> <kentfredric@×××××.com <mailto:kentfredric@×××××.com>> wrote:
>
> On 10 February 2016 at 02:14, Daniel Campbell <zlg@g.o
> <mailto:zlg@g.o>> wrote:
>> Another concern, though, is it'd result in something similar.
>> Instead of "cat/foo bar baz" and later removing 'baz', you'd have
>> "cat/foo bar ~baz" (with '~baz' as 'enable this if you need to').
>> You'd still have cruft left in your p.use file, and it would
>> achieve the same result as a well-commented file.
>
>
> Granted you'd still have the cruft in your config files, but it
> would become mostly-harmless cruft, not cruft that caused needless
> dependencies to get pulled into the dependency tree as a
> side-effect.
>
> And because it would be "only as needed", you could afford to use
> some of those "only if needed" useflags in a more global manner.
>
> For instance, I really don't want to globally define PYTHON_TARGETS
> to include python2_7, because it will simply install a lot of
> extra things I know I don't need.
>
> But if I could globally define something to the effect of
> "anything that wants python2.7 support can have it", then that's
> acceptable globally, because the effect would still turn things on
> automatically on a per-page level, not at a global level.
>
> So you could achieve the same results with much less syntax and
> much less effort.
>
>
> A distinct behavior for +USE (as opposed to -USE and USE) would
> fit better than "~USE" IMHO, where the plus means "add if (and only
> if) required" and would cascade through dependencies, so if I merge
> e.g. app-portage/pfl with USE="+PYTHON_TARGETS_PYTHON2_7" it would
> apply that to dependencies as required. ~USE might fit for
> something like "~PYTHON_TARGETS_PYTHON3", where it would select the
> greatest flag matching that prefix, and would therefore
> automatically keep packages that have 3_2, 3_3, 3_4, 3_5 using
> whatever is the latest unmasked flag. Could potentially combine the
> prefixes, e.g. "~+PYTHON_TARGETS_PYTHON3" to both select the
> greatest python version AND cascade to dependencies.

The ~ was just a spitballed idea. It's really not important *what* the
symbol is, it's just that one would be required.

- -- 
Daniel Campbell - Gentoo Developer
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