/**
  * Property read access.
  * 
  * @param string $propertyName Name of the property.
  * @return mixed Value of the property or null.
  *
  * @throws ezcBasePropertyNotFoundException
  *         If the the desired property is not found.
  * @ignore
  */
 public function __get($propertyName)
 {
     switch ($propertyName) {
         case "cascade":
             return $this->properties[$propertyName];
         default:
             return parent::__get($propertyName);
     }
 }