sub routine1
  {
    my($arg1,$arg2) = @_;
      ...
    return $result;
  }


##</code><code>##

{
  my %cached_results;

sub routine1
  {
    my($arg1,$arg2) = @_;
    return $cached_results{"$arg1||$arg2"}
            if(defined $cached_results{"$arg1||$arg2"});
      ...
    $cached_results{"$arg1||$arg2"} = $result;
    return $result;
  }

sub clear_cache1
  {
    %cached_results = ();
  }
}