my %hash=(qr{([0-4])}=>"foo", a=>"foo2");
$_=2;
for my $re (keys %hash) {
P "re=%s, ref=%s", $re, ref $re;
P "match:(%s) %s", $1, $hash{$re} if /$re/;
}
'
re=a, ref=
re=(?^:([0-4])), ref=
match:(2) foo