As mentioned elsewhere, you can use recursion:
sub foo
{
my ($hash, @path) = @_;
while (my ($k, $v) = each %$hash) {
if (ref $v eq 'HASH') {
foo($v, @path, $k);
} else {
# whatever
}
}
}
You can also use "eval" to build up the loops (hand-waving a bit):
$depth = compute_hash_depth;
$code = '...';
for (reverse 1..$depth) {
my $prev = $_-1;
$code = "while (my (\$k$_, \$v$_) = each \$v$prev) { $code }";
}
eval $code;
In general, when you want nested loops and don't know how many beforehand, recursion is easiest.