Altering the Return Value: Prewrappers

• Here's the list context code:

 $prereturn = $return = [];
 () = $wrapper{pre}->(@_,$return) if $wrapper{pre};
 if (ref $return eq 'ARRAY' && $return == $prereturn && !@$return) {
 $return = [ &$original ];
 () = $wrapper{post}->(@_, $return)
 if $wrapper{post};
 }
 return ref $return eq 'ARRAY' ? @$return : ($return);

• The if test handles pre-emption

  • If $return is overwritten with a new arrayref, $return == $prereturn test will fail