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Postings from August 2002
I ran across this in looking at tidying up old bugs. It seems like things are backwards below -- hyper-operation is a language-level shorthand for iteration over a container, so there's no reason for the container's vtable methods to be "hyper". Actually, it seems like there are at least a couple ways in which pushing this responsibility onto vtable methods may not be the best way: if we "hype" non-vtable methods, we have to handle explicit iteration in bytecode; and if we hyper-operate on tied variables, they have to re-implement this looping behavior in their add, etc methods. It looks like the standard perl5 behavior is implemented by the current vtable methods (hyping done separately), but I wanted to make sure we were on the same page before closing the bug. /s On Wed, 14 Aug 2002, David M. Lloyd wrote: > [what PerlArray vtable methods should do for "$x = @a + @b"] > I thought about this more. Here's a brain dump: > > Here's how I'd expect these expressions to be executed internally, in > gross pseudocode, ignoring for the moment the multimethod vaporware: > > $r = $a + $b; # $a->add($a, $b, $r) > $r = @a + $b; # $t = @a->get_pmc(@a); $t->add($t, $b, $r) > $r = $a + @b; # $t = @b->get_pmc(@b); $t->add($a, $t, $r) > $r = @a + @b; # $t = @a->get_pmc(@a); $u = @b->get_pmc(@b); $t->add($t, $u, $r); > @r = $a ^+ $b; # Something that makes one-elment arrays and > # uses add method on array object? Or perhaps > # error > @r = @a ^+ $b; # Does this distribute? If so, > # @a->add(@a, $b, @r) else see above > @r = $a ^+ @b; # See above > @r = @a ^+ @b; # @a->add(@a, @b, @r), easyThread Previous