I'm going to quibble with your advice regarding exists, which could be right or wrong depending on how one reads it. (I don't doubt that your understanding is correct, but I think others might read it differently than you intended.) Autovivification (the creation of intermediate references) is not prevented by using exists, so exists $h{1}{2} still creates $h{1}.

To prevent autovivification, one would have to test exists $h{1} and only if it were true, examine $h{1}{2}. However, they could just test whether $h{1} were true and get pretty much the same result -- if it didn't exist before, it won't exist after. The only difference in using exists is if $h{1} has a non-reference value like zero, empty string, or undef. It seems a little odd to dereference it in those cases. Perhaps a better idea would be to test it with ref.

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In reply to Re^2: Looping through a hash reference is creating a key...? by Roy Johnson
in thread Looping through a hash reference is creating a key...? by the_slycer

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