Language/05_Variables/1_Evaluation_of_Implicit_Variable_Getters_A01_t02.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 Let d be the declaration of a variable v.  If d is a local or
 * instance variable, then the invocation of the implicit getter of v
 * evaluates to the value stored in v.
 * If d is a static or library variable then the implicit getter method of v
 * executes as follows:
 * Non-constant variable declaration with initializer. If d is of one of the
 * forms var v = e; , T v = e; , final v = e; , final T v = e; , static v = e;
 * ,static T v = e; , static final v = e;  or static final T v = e; and no
 * value has yet been stored into v then the initializer expression e is
 * evaluated. If, during the evaluation of e, the getter for v is invoked,
 * a CyclicInitializationError is thrown. If the evaluation succeeded yielding
 * an object o, let r = o, otherwise let r = null. In any case, r is stored
 * into v. The result of executing the getter is r.
 * Constant variable declaration. If d is of one of the forms const v = e; ,
 * const T v = e; , static const v = e;  or static const T v = e; the result
 * of the getter is the value of the compile time constant e. Note that a
 * compile time constant cannot depend on itself, so no cyclic references can
 * occur. Otherwise
 * Variable declaration without initializer. The result of executing the
 * getter method is the value stored in v.
 * @description Checks that if during the evaluation of e, the getter for v
 * is invoked, a CyclicInitializationError is thrown. Also expects that
 * after that the result of getter is [:null:]
 * @author msyabro
 * @reviewer iefremov
 */
import "../../Utils/expect.dart";

f(func) {
  try {
    throw 1; // caugth exceptions do not matter
  } on int catch (e) {
    func();
  }
}

class C {
  static var sVar = f(() => sVar);
  static int sTyped = f(() => sTyped);
  static final sFinal = f(() => sFinal);
  static final int sFinalTyped = f(() => sFinalTyped);
}


main() {
  Expect.throws(() => C.sVar, (e) => e is CyclicInitializationError);
  Expect.equals(null, C.sVar);

  Expect.throws(() => C.sTyped, (e) => e is CyclicInitializationError); 
  Expect.equals(null, C.sTyped);

  Expect.throws(() => C.sFinal, (e) => e is CyclicInitializationError); 
  Expect.equals(null, C.sFinal);

  Expect.throws(() => C.sFinalTyped, (e) => e is CyclicInitializationError); 
  Expect.equals(null, C.sFinalTyped);
}