Language/Classes/Abstract_Instance_Members/override_no_named_parameters_t04.dart

// Copyright (c) 2011, 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.

/// @assertion Unless explicitly stated otherwise, all ordinary rules that apply
/// to methods apply to abstract methods.
/// It is a compile error if an instance method m1 overrides an instance member
/// m2 and m1 does not declare all the named parameters declared by m2.
/// @description Checks that no compile error is produced when the overriding
/// abstract method has the same set of named parameters as the non-abstract
/// instance method being overriden, but in a different order.
/// @author rodionov

import "../../../Utils/expect.dart";

class A {
  f({var x, var y}) { return x+y; }
}

abstract class C extends A {
  f({var y, var x});
}

class D extends C {
  f({var x, var y}) { return x-y; }
}

main() {
  A a = new A();
  Expect.equals(3, a.f(x:2, y:1));
  a = new D();
  Expect.equals(1, a.f(x:2, y:1));
}