public function setSimpleXmlClass($simplexmlclass)
    {
        $interfaces = class_implements($simplexmlclass);
        $interface  = sprintf('%s\%s', __NAMESPACE__, 'SimpleXmlConfigInterface');

        if (!in_array($interface, $interfaces)) {
            throw new \InvalidArgumentException(sprintf('SimpleXml class must implement %s', $interface));
        }
        $this->simplexmlclass = $simplexmlclass;
    }