The branch reset operator is a regex pattern extension added with Perl version 5.10. For those of you still clomping around in the pre-5.10 Stone Age, here's an old-school alternative:
c:\@Work\Perl\monks>perl -wMstrict -le
"for my $s (qw(/key/42 /key/ /24-99 /24- /24 /key/42-99)) {
my $parsed =
my ($id) =
grep defined,
$s =~ m{ \A (?: /key/ (\d+) | / (\d+) - \d+) \z }xms;
;;
print qq{'$s' -> }, $parsed ? qq{'$id'} : 'no id';
}
"
'/key/42' -> '42'
'/key/' -> no id
'/24-99' -> '24'
'/24-' -> no id
'/24' -> no id
'/key/42-99' -> no id
(Of course, this still works post-5.10!)
Give a man a fish: <%-{-{-{-<
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