| // Copyright (c) 2013, 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. |
| |
| library test.proxy_type; |
| |
| import 'dart:mirrors'; |
| import 'package:expect/expect.dart'; |
| |
| // This test is much longer that is strictly necessary to test |
| // InstanceMirror.type in the face of a reflectee overriding runtimeType, but |
| // shows a case where one might have legimate reason to override runtimeType. |
| // See section 2.2 in Mark Miller's Robust Composition: Towards a Unified |
| // Approach to Access Control and Concurrency Control. |
| |
| class Alice { |
| Bob bob = new Bob(); |
| Carol carol = new Carol(); |
| sayFooUnattenuated() { |
| bob.foo(carol); |
| } |
| |
| sayFooAttenuated() { |
| bool enabled = true; |
| bool gate() => enabled; |
| bob.foo(new CarolCaretaker(carol, gate)); |
| enabled = false; // Attenuate a capability |
| } |
| |
| sayBar() { |
| bob.bar(); |
| } |
| } |
| |
| class Bob { |
| Carol savedCarol; |
| foo(Carol carol) { |
| savedCarol = carol; // Store a capability |
| carol.foo(); |
| } |
| |
| bar() { |
| savedCarol.foo(); |
| } |
| } |
| |
| class Carol { |
| foo() => 'c'; |
| } |
| |
| typedef bool Gate(); |
| |
| class CarolCaretaker implements Carol { |
| final Carol _carol; |
| final Gate _gate; |
| CarolCaretaker(this._carol, this._gate); |
| |
| foo() { |
| if (!_gate()) throw new NoSuchMethodError(this, #foo, [], {}); |
| return _carol.foo(); |
| } |
| |
| Type get runtimeType => Carol; |
| } |
| |
| main() { |
| Alice alice1 = new Alice(); |
| alice1.sayFooUnattenuated(); |
| alice1.sayBar(); // Bob still has authority to use Carol |
| |
| Alice alice2 = new Alice(); |
| alice2.sayFooAttenuated(); |
| Expect.throwsNoSuchMethodError(() => alice2.sayBar(), |
| 'Authority should have been attenuated'); |
| |
| // At the base level, a caretaker for a Carol masquerades as a Carol. |
| CarolCaretaker caretaker = new CarolCaretaker(new Carol(), () => true); |
| Expect.isTrue(caretaker is Carol); |
| Expect.equals(Carol, caretaker.runtimeType); |
| |
| // At the reflective level, the caretaker is distinguishable. |
| Expect.equals(reflectClass(CarolCaretaker), reflect(caretaker).type); |
| } |