On Sat, 8 Jul 2017 13:01:39 +0100 Ciaran McCreesh <ciaran.mccre...@googlemail.com> wrote:
> On Sat, 8 Jul 2017 13:49:56 +0200 > Alexis Ballier <aball...@gentoo.org> wrote: > > On Sat, 8 Jul 2017 12:26:59 +0200 > > Ulrich Mueller <u...@gentoo.org> wrote: > > > | * An any-of group (||) evaluates to true if at least one of the > > > | items in it evaluates to true. > > > | * An exactly-one-of group (^^) evaluates to true if exactly one > > > of | the items in it evaluates to true, and all the remaining > > > items | evaluate to false. > > > | * An at-most-one-of group (??) evaluates to true if at most one > > > of | the items in it evaluates to true. > > > > > > It should be added that any empty group (|| or ^^ or ??) > > > evalutates to true, because that's what PMS specifies: > > > https://projects.gentoo.org/pms/6/pms.html#x1-780008.2 > > > > A bit OT, but that is *definitely* counter intuitive. What's the > > rationale and usecase behind this ? > > Annoying special cases like || ( foo? ( ... ) bar? ( ... ) ) . The > original reason was that old versions of Portage would simply remove > unmet "flag? ( )" blocks internally. It was kept in EAPI 0 because > stuff in the tree used it back then. > Wasn't REQUIRED_USE something completely new with no prior usage in EAPI 3 ?
