public static function deleteAtShutdown($filename, $register = true,
                                            $secure = false)
    {
        /* Initialization of variables and shutdown functions. */
        if (!self::$_shutdownreg) {
            register_shutdown_function(array(__CLASS__, 'shutdown'));
            self::$_shutdownreg = true;
        }

        $ptr = &self::$_shutdowndata;
        if ($register) {
            $ptr['paths'][$filename] = true;
            if ($secure) {
                $ptr['secure'][$filename] = true;
            }
        } else {
            unset($ptr['paths'][$filename], $ptr['secure'][$filename]);
        }
    }