public function getHandlers()
    {
        $filters = &gplcart_static('filter.handlers');

        if (isset($filters)) {
            return $filters;
        }

        $filters = array();
        $this->hook->attach('filter.handlers', $filters, $this);

        foreach ($filters as $id => &$filter) {
            $filter['filter_id'] = $id;
            $filter += array(
                'role_id' => array(),
                'status' => true,
                'module' => null
            );
        }

        return $filters;
    }