/**
  * Registers the directory $dir for removal when PHP shuts down.
  *
  * The directory and all of its contents will be removed recursively.
  *
  * @param string $dir
  */
 public static function registerForRemoval($dir)
 {
     if (self::$isRegistered === false) {
         register_shutdown_function(array("ezcMailParserShutdownHandler", "shutdownCallback"));
         self::$isRegistered = true;
     }
     self::$directories[] = $dir;
 }