The code @$x = map { $_ ||= "" } @$x; modifies the original values of @$x and the replaces @$x with those modified values. It is a bit redundant, like doing:

for(  @$x  ) {
    $_ ||= "";
}
@$x= @$x;
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Two good heuristics when using map:

1. Don't use map in a void context
2. Don't modify $_ inside of map

and you've broken rule 2 here.

This code @$x= map { defined($_) ? $_ : "" } @$x; avoids that problem.

        - tye (but my friends call me "Tye")