hphp/hack/test/typecheck/abstract_implement7.php

   1 <?hh // strict
   2 /**
   3  * Copyright (c) 2014, Facebook, Inc.
   4  * All rights reserved.
   5  *
   6  * This source code is licensed under the MIT license found in the
   7  * LICENSE file in the "hack" directory of this source tree.
   8  *
   9  *
  10  */
  11
  12 // Allow delayed implementation for abstract classes
  13
  14 interface IFace {
  15   public function foo(): int;
  16 }
  17
  18 // multiple layers
  19 abstract class AClass implements IFace {}
  20
  21 abstract class BClass extends AClass {}
  22 abstract class CClass extends BClass {}
  23 class DClass extends CClass {
  24   public function foo(): int {
  25     return 0;
  26   }
  27 }