public static function validateInstances($instances, $group = "") {
		if (sizeof ( $instances ) > 0) {
			$instance = current ( $instances );
			$class = get_class ( $instance );
			$cache = self::getClassCacheValidators ( $class, $group );
			if ($cache === false) {
				$members = self::fetch ( $class );
				self::initInstancesValidators ( $instance, $members, $group );
				$cache = self::$instanceValidators [$class];
			}
			return self::validateInstances_ ( $instances, $cache );
		}
		return [ ];
	}