Jonathan Worthington wrote:
Yup. To be able to implement Perl 6's cmp as an MMD method on the
junction, the ability to return a PMC as well as just a -1, 0 or 1 would
be handy. Otherwise we just special case the implementation of the <=>
and cmp operators to get junctions to thread through them. As you say,
it would be useful for other languages that want to hand back an
undefined value or something too. So perhaps a general mechanism is a
good thing.
say $allison.thoughts; # por favor :-)
Perl 6 junctions are special constructs, with special kinds of return
values. The Perl 6 operators will appropriately handle them, but
low-level Parrot operations won't always. There are plenty of cases
where HLL behavior is provided as HLL operators or functions made up of
a series of Parrot operations rather than a single low-level Parrot
operation, so this isn't any particular disadvantage for junctions.
(I'm fine with splitting out the comparison operators from cmp at some
point, if we have a significant case other than junctions that it makes
sense for. We don't currently.)
Allison
