Re: [gentoo-dev] Re: RFC: USE flags in virtuals, to allow a specific provider to be determined
On Sat, Jul 26, 2014 at 01:45:46PM -0400, Jonathan Callen wrote:
*snip*
If you want to say At most one of the flags 'foo', 'bar', and 'baz'
may be selected, then you say it like so (requires EAPI=5):
REQUIRED_USE=?? ( foo bar baz )
If you want to say Exactly one of the flags ..., then you use:
REQUIRED_USE=^^ ( foo bar baz )
And, as always, you can say At least one of the flags ... with:
REQUIRED_USE=|| ( foo bar baz )
While each of these can be written using the foo? ( !bar )-type
primitives, the messages portage outputs are generally better with
'??', '^^', and '||', as you might see something like:
The following REQUIRED_USE flag constraints are unsatisfied:
at-most-one-of ( foo bar baz )
Which is, in my opinion, more readable.
Now I understand what ciaranm was suggesting in pkg_pretend. Note, this
is not shell syntax, but it conveys the idea...
pkg_pretend() {
count=0
for x in foo bar bas; do
use $x count += 1
done
# Now, if count == 0 none of the flags are used, and
# if count 1 more than one is used, so die whenever appropriate
# with any error message you choose.
}
William
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Re: [gentoo-dev] Re: RFC: USE flags in virtuals, to allow a specific provider to be determined
El sáb, 26-07-2014 a las 08:05 +, Duncan escribió: Ian Stakenvicius posted on Fri, 25 Jul 2014 14:49:44 -0400 as excerpted: Hey all.. So, putting aside for now how much of a mess this would be to implement in the virtuals' ebuilds themselves, what do people think of changing the virtuals so that they contain an entry in IUSE for each provider that can satisfy it? The idea here is that the package satisfying a virtual could be optionally explicitly-chosen through package.use (or USE= in make.conf, perhaps) instead of having an entry in @world, that way if nothing depends on the virtual then it and the provider can be - --depclean'ed from the system. The idea is specifically NOT to have rdeps depend on these flags, that would undermine the whole purpose of the virtual; it would just be for end-users to set if they so chose. This may also help with getting portage to peg a virtual's provider to a specific package instead of constantly trying to switch from one to another, ie, how systemd kept getting pulled in, in relation to the upower virtual. What about handling each such virtual_USE as a USE_EXPAND? VIRTUAL_* as reserved-namespace USE_EXPAND would give us full backward compatibility along with an immediately identifiable namespace and virtually (heh) no possibility of confusion with other configuration. Continuing with the earlier virtual/krb5 example, we'd have VIRTUAL_KRB5, with possible settings in make.conf of: VIRTUAL_KRB5=mit-krb5 VIRTUAL_KRB5=heimdal Virtually no possibility of confusion with normal USE flags, and the matching virtual would be immediately identifiable, so no possibility of getting confused on what it applies to, either. I would also prefer to use USE_EXPAND to not mix normal USEs with virtuals... but I would go with using the same VIRTUAL variable for all virtuals, otherwise people will end up having dozens of VIRTUAL_ statements in make.conf (one per virtual package)
Re: [gentoo-dev] Re: RFC: USE flags in virtuals, to allow a specific provider to be determined
Dnia 2014-07-26, o godz. 08:05:32 Duncan 1i5t5.dun...@cox.net napisał(a): Ian Stakenvicius posted on Fri, 25 Jul 2014 14:49:44 -0400 as excerpted: Hey all.. So, putting aside for now how much of a mess this would be to implement in the virtuals' ebuilds themselves, what do people think of changing the virtuals so that they contain an entry in IUSE for each provider that can satisfy it? The idea here is that the package satisfying a virtual could be optionally explicitly-chosen through package.use (or USE= in make.conf, perhaps) instead of having an entry in @world, that way if nothing depends on the virtual then it and the provider can be - --depclean'ed from the system. The idea is specifically NOT to have rdeps depend on these flags, that would undermine the whole purpose of the virtual; it would just be for end-users to set if they so chose. This may also help with getting portage to peg a virtual's provider to a specific package instead of constantly trying to switch from one to another, ie, how systemd kept getting pulled in, in relation to the upower virtual. What about handling each such virtual_USE as a USE_EXPAND? VIRTUAL_* as reserved-namespace USE_EXPAND would give us full backward compatibility along with an immediately identifiable namespace and virtually (heh) no possibility of confusion with other configuration. USE_EXPAND are global by definition. We ought fight with the abuse of USE_EXPAND rather than make another abuse legitimate. Especially that you're going to increase a lot of new variables quickly for no really good reason. -- Best regards, Michał Górny signature.asc Description: PGP signature
Re: [gentoo-dev] Re: RFC: USE flags in virtuals, to allow a specific provider to be determined
On Sat, 26 Jul 2014 10:53:21 +0200 Michał Górny mgo...@gentoo.org wrote: USE_EXPAND are global by definition. Naah. They're global by a Portage configuration file limitation. In the old days, USE flags were global too... -- Ciaran McCreesh signature.asc Description: PGP signature
Re: [gentoo-dev] Re: RFC: USE flags in virtuals, to allow a specific provider to be determined
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 On 26/07/14 04:05 AM, Duncan wrote: Ian Stakenvicius posted on Fri, 25 Jul 2014 14:49:44 -0400 as excerpted: Hey all.. So, putting aside for now how much of a mess this would be to implement in the virtuals' ebuilds themselves, what do people think of changing the virtuals so that they contain an entry in IUSE for each provider that can satisfy it? The idea here is that the package satisfying a virtual could be optionally explicitly-chosen through package.use (or USE= in make.conf, perhaps) instead of having an entry in @world, that way if nothing depends on the virtual then it and the provider can be - --depclean'ed from the system. The idea is specifically NOT to have rdeps depend on these flags, that would undermine the whole purpose of the virtual; it would just be for end-users to set if they so chose. This may also help with getting portage to peg a virtual's provider to a specific package instead of constantly trying to switch from one to another, ie, how systemd kept getting pulled in, in relation to the upower virtual. What about handling each such virtual_USE as a USE_EXPAND? VIRTUAL_* as reserved-namespace USE_EXPAND would give us full backward compatibility along with an immediately identifiable namespace and virtually (heh) no possibility of confusion with other configuration. Continuing with the earlier virtual/krb5 example, we'd have VIRTUAL_KRB5, with possible settings in make.conf of: VIRTUAL_KRB5=mit-krb5 VIRTUAL_KRB5=heimdal Virtually no possibility of confusion with normal USE flags, and the matching virtual would be immediately identifiable, so no possibility of getting confused on what it applies to, either. *shrug*, sure.. effectively we just start using IUSE=virtual_krb5_mit-krb5 instead of mit-krb5 but yes this would work too. -BEGIN PGP SIGNATURE- Version: GnuPG v2 iF4EAREIAAYFAlPTrbUACgkQ2ugaI38ACPAbcAD/VapV0WR+Z7aWcyHeehHzoHSw Qi8o+EDkQpakD3bVVtAA/0WSTPsPmVWHq3Fn0iITXbprHsKWMV+mXPN23nbpUdzf =aE4s -END PGP SIGNATURE-
