Language/Expressions/Type_Test/definition_t10.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 v be a local variable or a formal parameter. An is-expression
 * of the form v is T shows that v has type T iff T is more specific than the
 * type S of the expression v and both T != dynamic and S != dynamic.
 * @description Checks that if T is more specific than S, and neither of them
 * is dynamic, then is-expression shows that v has type T.
 * @static-clean
 * @author ilya
 */

class C {}
class D extends C { f() {} }

f(C x) {
  C y = x;

  x is D ? x.f() : null; // formal parameter
  y is D ? y.f() : null; // local variable
}

main() {
  f(new D());
}