my @vars = (7, 12, 49, 44);
sub bubble_sort {
   my $rfunc = shift;
   for my $i (1 .. $#vars) {
      for my $j (0 .. $i-1) {
         if (&($rfunc)($vars[i], $vars[j])) {
            my $t=$vars[i]; $vars[$i]=$vars[$j]; $vars[$j]=$t;
         }
      }
   }
}