ike:

The return here errors if called as: name(\$var)

sub name {
   my ($arg) = @_;
   if (not ref $arg) {
      $arg = \$arg;
   }

   # Do stuff.
   $$arg = 'changed';

   return $$arg;
}
[download]

If I remove the return $$arg; it still works in either context because of that sneaky little 'return the last value' trick :D

Thanks!