这样的写法是如何形成的

/**     * 控制器调度     *     */    private static function control() {        //二级域名        if ($GLOBALS['setting_config']['enabled_subdomain'] == '1' && $_GET['act'] == 'index' && $_GET['op'] == 'index') {            $store_id = subdomain();            if ($store_id > 0)                $_GET['act'] = 'show_store';        }        $act_file = realpath(BASE_PATH . '/control/' . $_GET['act'] . '.php');        $class_name = $_GET['act'] . 'Control';        if (!@include($act_file)) {            if (C('debug')) {                throw_exception("Base Error: access file isn't exists!");            } else {                showMessage('抱歉！您访问的页面不存在', '', 'html', 'error');            }        }        if (class_exists($class_name)) {            $main = new $class_name();            $function = $_GET['op'] . 'Op';            if (method_exists($main, $function)) {                $main->$function();            } elseif (method_exists($main, 'indexOp')) {                $main->indexOp();            } else {                $error = "Base Error: function $function not in $class_name!";                throw_exception($error);            }        } else {            $error = "Base Error: class $class_name isn't exists!";            throw_exception($error);        }    }​