if ( $compressor ) {
    my $namespace = 'My::' . $compressor;
    if ( ! eval "package $namespace; use $compressor; 1;" ) {
      die "Could not load $compressor - $@";
    } else {
      ...
    }
  }

##</code><code>##

  } else {
    my $compress   = "My::$compressor\::compress";

    no strict 'refs';
    my $compressed = &$compress( $raw ); 
    use strict 'refs';
  }