public function getInstalled()
    {
        if (!$this->db->isInitialized()) {
            return array();
        }

        $modules = &gplcart_static('module.installed.list');

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

        $options = array(
            'index' => 'module_id',
            'unserialize' => 'settings'
        );

        return $modules = $this->db->fetchAll('SELECT * FROM module', array(), $options);
    }