How to iterate through Hash (of Hashes) in Perl?

Question

I have Hash where values of keys are other Hashes.

Example: {'key' => {'key2' => {'key3' => 'value'}}}

How can I iterate through this structure?

Answer 1

Is this what you want? (untested)

sub for_hash {
    my ($hash, $fn) = @_;
    while (my ($key, $value) = each %$hash) {
        if ('HASH' eq ref $value) {
            for_hash $value, $fn;
        }
        else {
            $fn->($value);
        }
    }
}

my $example = {'key' => {'key2' => {'key3' => 'value'}}};
for_hash $example, sub {
    my ($value) = @_;
    # Do something with $value...
};