protected function fetch($id, $name, $cache_id, $compile_id, &$content, &$mtime)
    {
        $this->fetch->execute(array('id' => $id));
        $row = $this->fetch->fetch();
        $this->fetch->closeCursor();
        if ($row) {
            $content = $row['content'];
            $mtime = strtotime($row['modified']);
        } else {
            $content = null;
            $mtime = null;
        }
    }