hphp/hack/test/typecheck/this_datatype1.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 interface DataTypeImplProvider<Timpl> {
  13   public function impl(): Timpl;
  14 }
  15
  16 interface DataType<Tk, Tv, Timpl>
  17   extends DataTypeImplProvider<Timpl> {
  18
  19   public function get(Tk $id): Tv;
  20 }
  21
  22 abstract class AbstractDataType<Tk, Tv> implements DataTypeImplProvider<this> {
  23   final static public function at(): DataType<Tk, Tv, this> {
  24     invariant_violation('');
  25   }
  26
  27   final public function impl(): this {
  28     return $this;
  29   }
  30 }
  31
  32 class MyThingDataType extends AbstractDataType<int, string> {
  33   public function get(int $v): string {
  34     return (string)$v;
  35   }
  36
  37   public function customMethod(): void {
  38   }
  39 }
  40
  41 function myFunc(): string {
  42   MyThingDataType::at()->impl()->customMethod();
  43   return MyThingDataType::at()->get(1);
  44 }