Language/12_Expressions/12_Instance_Creation/2_Const_A08_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 Evaluation of e proceeds as follows:
 * First, if e is of the form const T.id(a1, .., an, xn+1: an+1, …, xn+k: an+k)
 * then let i be the value of the expression new T.id(a1, .., an, xn+1: an+1, …, xn+k: an+k).
 * Otherwise, e must be of the form  const T(a1, .., an, xn+1: an+1, …, xn+k: an+k),
 * in which case let i be the result of evaluating new T(a1, .., an, xn+1: an+1, …, xn+k: an+k) .
 * Then:
 * - If during execution of the program, a constant object expression has already evaluated
 *   to an instance j of class R with type arguments Vi , 1<=i<=m, then:
 *    – For each instance variable f of i, let vif be the value of the field f in
 *      i, and let vjf be the value of the field f in j. If identical(vif , vjf ) for
 *      all fields f in i, then the value of e is j, otherwise the value of e is i.
 * - Otherwise the value of e is i.
 * In other words, constant objects are canonicalized.
 * @description Checks that a fresh instance of an object is created
 * if any of the fields in i are not identical to the fields in j.
 * @author msyabro
 * @reviewer rodionov
 */
import "../../../Utils/expect.dart";

class A {
  const A(p1): x = p1, y = 3;
  final x;
  final y;
}

main() {
  var o1 = const A(1);
  var o2 = const A(2);
  Expect.isFalse(identical(o1, o2));

  for(int i = 0; i < 10; i++) {
    Expect.identical(o1, const A(1));
    Expect.isFalse(identical(const A(1), o2));
    Expect.identical(o2, const A(2));
    Expect.isFalse(identical(const A(2), o1));
  }
}