/**
  * Constructor for Zend_Gdata_Books_Extension_PreviewLink which
  * Describes a preview link
  *
  * @param string|null $href Linked resource URI
  * @param string|null $rel Forward relationship
  * @param string|null $type Resource MIME type
  * @param string|null $hrefLang Resource language
  * @param string|null $title Human-readable resource title
  * @param string|null $length Resource length in octets
  */
 public function __construct($href = null, $rel = null, $type = null, $hrefLang = null, $title = null, $length = null)
 {
     foreach (Zend_Gdata_Books::$namespaces as $nsPrefix => $nsUri) {
         $this->registerNamespace($nsPrefix, $nsUri);
     }
     parent::__construct($href, $rel, $type, $hrefLang, $title, $length);
 }

 public function __construct($href = null, $rel = null, $type = null, $hrefLang = null, $title = null, $length = null)
 {
     $this->registerAllNamespaces(Zend_Gdata_Books::$namespaces);
     parent::__construct($href, $rel, $type, $hrefLang, $title, $length);
 }