On Thu, Dec 22, 2005 at 02:53:39PM +0100, TSa wrote:
> HaloO,
>
> Luke Palmer wrote:
> >Recently, I believe we decided that {} should, as a special case, be
> >an empty hash rather than a do-nothing code, because that's more
> >common.
>
> Ups, is that distinction needed eagerly? Wouldn't the return value
> of a do-nothing code return a value that when coerced into hashness
> result in an empty hash? Avoiding this superflous call is more of
> interest to the optimizer than code correctness. OTOH, implementing
> an empty block is easy as well.
Well, I assume that the do-nothing sub is assigned into the variable, and
gets re-evaluated each time the variable is use. Which would mean that you'd
get a new (different) empty hash each time. Whereas an empty hash constructor
gives you a hash reference to keep. (not just for Christmas)
It's like the autovivification bug:
sub stuff {
my $h = shift;
$h->{k}++;
}
my $a;
$a->{$_}++ for @ARGV;
stuff($a);
print "$a->{k}\n";
__END__
Nicholas Clark
