static function countWithSubscriberID( $subscriberID, $languageID =false , $enabled = false )
    {
        $cond = array();
        $cond['subscriber_id'] = $subscriberID;
        if ( $enabled !== false )
        {
            $cond['enabled'] = $enabled;
        }
        if ( $languageID !== false )
        {
            $cond['language_id'] = $languageID;
        }
        $count = eZPersistentObject::count( self::definition(), $cond );
        return $count;
    }