protected function searchController(
        /*# string */ $controller,
        /*# string */ $action
    )/*# : callable */ {
        $controllerName = $controller . $this->controller_suffix;
        $actionName = $action . $this->action_suffix;
        foreach ($this->namespaces as $ns) {
            $class = $ns . '\\' . $controllerName;
            if (class_exists($class)) {
                $obj = new $class();
                return [$obj, $actionName];
            }
        }
        throw new LogicException(
            Message::get(Message::RTE_HANDLER_UNKNOWN, $controller),
            Message::RTE_HANDLER_UNKNOWN
        );
    }