rfc:returntypehint

Request for Comments: Return type-hint

Introduction

The purpose of the RFC is to discuss about the return type hint utility on PHP.

Differences from the old proposal

  • The old proposal (return and param type-hint) was introducing some keywords (the type names), with this new proposal there is no such BC.
  • The new proposal has a better error message, identifying where the function/method was called.
  • Added generic “numeric”, “scalar” types
  • No needed strange syntax to solve parser conflicts

Examples

Using "scalar" type-hint

<?php
 
function scalar abc($x = NULL) {
	return $x;
}
 
var_dump(abc(1));  // int(1)
var_dump(abc(1.)); // float(1)
var_dump(abc());
/*
PHP Catchable fatal error:  The returned value must be of the type scalar,
called in ... on line 9 and returning in ... on line 4
*/

Using an user class type

<?php
 
class Bar { }
 
class Foo extends Bar {
	public function Bar test($x) {
		return $x;
	}
}
 
$foo = new Foo;
$foo->test($foo);         // ok
$foo->test(new stdClass); // fail
/*
PHP Catchable fatal error:  The returned value should be instance of Bar,
called in ... on line 13 and returning in ... on line 7
*/

Interface defining the return type-hint

<?php
 
interface ITest {
	function string bar();
}
 
class Foo implements ITest {
	public function int bar() {
	}
}
// PHP Fatal error:  Declaration of Foo::bar() must be compatible with that of ITest::bar() in ... on line 7

Using a namespaced class

<?php
 
namespace foo {
class foo { }
class bar extends foo { }
}
 
namespace bar {
class bar {
	public function \foo\foo test() {
		return new \foo\bar;
	}
}
 
$bar = new bar;
$bar->test(); // ok
}

Reflection

  • See below some information that will be possible to be get using Reflection.

Using a class type

<?php
 
interface Test {
 
}
 
class foo implements Test {
	function Test test() {
		return new foo;
	}
}
 
$func = new ReflectionMethod('foo::test');
var_dump($func->getReturnTypeHint());   // "Test"
var_dump($func->returnsObject());       // true

PHP native types

<?php
 
function scalar abc($x = NULL) {
	return $x;
}
 
$func = new ReflectionFunction('abc');
var_dump($func->getReturnTypeHint()); // scalar
var_dump($func->returnsScalar());     // true

Using "self" as type

<?php
 
class foo {
	function self bar() {
		return new foo;
	}
}
 
$func = new ReflectionMethod('foo::bar');
var_dump($func->getReturnTypeHint()); // foo
var_dump($func->returnsObject());     // true

Patch

rfc/returntypehint.txt · Last modified: 2011/04/06 12:59 (external edit)