/**
    * Load the extra database fields defined in extraStatics.
    */
   function loadExtraStatics() {
      // Don't apply DB fields if the parent object has this extension too
      if(singleton(get_parent_class($this->owner))->extInstance($this->class)) return;
   
      $fields = $this->extraStatics();
      $className = $this->owner->class;

      if($fields) {
         foreach($fields as $relationType => $fields) {
            if(in_array($relationType, self::$decoratable_statics)) {
               eval("$className::\$$relationType = array_merge((array){$className}::\$$relationType, (array)\$fields);");
               $this->owner->set_stat($relationType, eval("return $className::\$$relationType;"));
            }
            
            // clear previously set caches from DataObject->hasOwnTableDatabaseField()
            $this->owner->set_uninherited('_cache_hasOwnTableDatabaseField', null);
         }
      }
   }

      /**
    * Set the owner of this decorator.
    * @param DataObject $owner
    */
   function setOwner(Object $owner) {
      if(!($owner instanceof DataObject)) {
         user_error(sprintf(
            "DataObjectDecorator->setOwner(): Trying to decorate an object of class '%s' with '%s',
            only Dataobject subclasses are supported.",
            get_class($owner), $this->class),
            E_USER_ERROR
         );
         return false;
      }
      
      parent::setOwner($owner);
   }
   
   /**
    * Load the extra database fields defined in extraStatics.
    */
   function loadExtraStatics() {
      // Don't apply DB fields if the parent object has this extension too
      if(Object::has_extension($this->owner->parentClass(), $this->class)) return;

      if($fields = $this->extraStatics()) {
         foreach($fields as $relation => $fields) {
            if(in_array($relation, self::$decoratable_statics)) {
               // Can't use add_static_var() here as it would merge the array rather than replacing
               Object::set_static (
                  $this->owner->class,
                  $relation,
                  array_merge((array) Object::get_static($this->owner->class, $relation), $fields)
               );
            }
         }
         
         DataObject::$cache_has_own_table[$this->owner->class] = null;
         DataObject::$cache_has_own_table_field[$this->owner->class] = null;
      }
   }