Re: [gentoo-user] Re: How to easily find out what USE flags are redundant in make.conf and package.use?

[Alan McKinnon]

On Sun, 2 Oct 2011 10:53:46 -0400
Michael Mol <mikemol@×××××.com> wrote:

> On Sun, Oct 2, 2011 at 7:58 AM, Alan McKinnon
> <alan.mckinnon@×××××.com> wrote:
> > On Sun, 02 Oct 2011 06:36:54 -0500
> > Dale <rdalek1967@×××××.com> wrote:
> >> Alan McKinnon wrote:
> >> > On Sun, 02 Oct 2011 05:13:49 -0500
> >> > Dale<rdalek1967@×××××.com>  wrote:
> > You often mention the attraction of Gentoo is you get only what you
> > want. But, consider this; if you put flags routinely in make.conf
> > you lose most of that benefit. You end up with the equivalent of
> > Mandrake where you complied it yourself, not the binary distro.
> >
> > USE="<every possible flag enabled>" emerge something and
> > yum install something and pretty much equivalent in terms of end
> > result.
>
> I'm actually very much in Dale's usage pattern here. If there's a
> feature I want, and it's a globally-valid USE flag (such as, say,
> ipv6), I put it in make.conf. If there's a feature I want, and it's
> package-specific, it goes in package.use. If there's a feature I want,
> it's a globally-valid USE flag, but I *don't* want it in a particular
> package (say, X in vim), the enabler goes in make.conf, the disabler
> goes in packages.use; for 90% of packages, I want that support.
>
> So that's not USE=<every possible flag enable>, that's USE=<all the
> global flags I want enabled>.
 

As with all things in life,  USE flags require intelligence, common
sense and familiarity to use to best advantage. Not all global USE
flags are equal or used in the same way!

USE="ipv6" is mostly global and single-meaning. ipv6 support means
just that - ipv6 support. For a daemon, that would be listen on an
ipv6 interface and talk it back. For config tools, it's " set up
interfaces and routes ipv6 style". It's hard to come up with a meaning
for the flag that's outside that narrow range; it's equally hard to
come up with a reason to use in package.use. Maybe disable it for a
package that supports ipv6 but is known to be broken in it's support.

USE="perl python" is a very different kettle of fish. While also
global (i.e. used in a similar way by more than x number of ebuilds),
the meaning in use can differ wildly. It can mean to build support
for extra tools written in perl|python, or build language bindings, or
use language bindings and possibly many things. These flags can benefit
from being used in package.use - whereas you probably want ipv6 support
everywhere if used, perl|python isn't used the same way.

Your post indicates you already know this :-)

I mentioned it to Dale to illuminate that just because a flag is
*defined* globally doesn't mean you have to *use* it globally. And the
reverse is also true - overlays often have flags used in many ebuilds,
always with the same meaning (e17 is like this), but are not global in
use.desc. My own make.conf has many of these flags.

Sometimes I wish Gentoo would express these distinctions. Then I think
about what it would take to do that, and shelf the idea :-)

--
Alan McKinnnon
alan.mckinnon@×××××.com