You are right. I just benchmarked it. The overhead of
the maps far outweighs the cost of the sort. In fact it
is so slow I will have to ask p5p about it. Here is my
test:
use strict;
use Benchmark;
use vars qw(%hash %test);
for (1..1000) {
$hash{"key$_"}{this} = "num$_";
}
%test = (
schwartz => sub {
my @sorted = map $_->[0],
sort {$a->[1] cmp $b->[1]}
map [$_, $hash{$_}{this}], keys %hash;
},
straight => sub {
my @sorted = sort
{ $hash{$a}{this} <=> $hash{$b}{this} }
keys %hash;
},
stupid => sub {
my @sorted = sort
{
my $foo = [$a, $hash{$a}{this}];
$hash{$a}{this} <=> $hash{$b}{this}
} keys %hash;
},
);
timethese (-1, \%test);
Believe it or not, stupid is several times faster for me
than schwartz. IMO there is simply no possible good reason
for that!
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