If you are looking to create an exact copy of any perl data structure, then you can use the dclone() function from Storable.pm

Obviously if you clone a big data structure that way it will take a while, and will burn a lot of memory, so if you are looking to change a small amount of a large data structure, you may want to consider a more advanced algorithm.

Don't do what I did when I was a novice which is to write code like this:

foreach my $key1 (keys %$foo)
{
    foreach my $key2 (keys %{$foo->{$key1}})
    {
        # etc....

        $bar->[$idx1][$idx2]..[$idx5] = $foo->{$key1}{$key2}..{$key5};
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