What does `$hash{$key} |= {}` do in Perl?
I was wrestling with some Perl that uses hash references. In the end it turned out that my problem was the line: $myhash{$key} |= {}; That is, "assign $myhash{$key} a reference to an empty hash, unless it already has a value". Dereferencing this and trying to use it as a hash reference, however, resulted in interpreter errors about ...