|  | // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file | 
|  | // for details. All rights reserved. Use of this source code is governed by a | 
|  | // BSD-style license that can be found in the LICENSE file. | 
|  |  | 
|  | abstract class Interface<T> { | 
|  | factory Interface() = Factory<T>; | 
|  | factory Interface.withArg(T value) = Factory<T>.withArg; | 
|  | } | 
|  |  | 
|  | class Factory<T> implements Interface<T> { | 
|  | factory Factory() { | 
|  | return Factory._(); | 
|  | } | 
|  |  | 
|  | factory Factory.withArg(T value) { | 
|  | return Factory._(); | 
|  | } | 
|  |  | 
|  | Factory._(); | 
|  | } | 
|  |  | 
|  | main() { | 
|  | new Interface<int>(); | 
|  | new Interface<int>.withArg(4); | 
|  | } |