function fromXmlFile($descfile)
    {
        if (!file_exists($descfile) || !is_file($descfile) || !is_readable($descfile) ||
             (!$fp = fopen($descfile, 'r'))) {
            require_once 'PEAR.php';
            return PEAR::raiseError("Unable to open $descfile");
        }

        // read the whole thing so we only get one cdata callback
        // for each block of cdata
        fclose($fp);
        $data = file_get_contents($descfile);
        return $this->fromXmlString($data);
    }