%$hash_ref = (); makes more sense than undef-ing the hash. Undef-ing the hash says that you’re done with the hash. Assigning an empty list says you just want an empty hash.
%$hash_ref = (); makes more sense than undef-ing the hash. Undef-ing the hash says that you’re done with the hash. Assigning an empty list says you just want an empty hash.