PHP kézikönyv
Előző | 19. Fejezet. Classes and Objects (PHP 5) | Következő

# Type Hinting

PHP 5 introduces Type Hinting. Functions are now able to force parameters to be objects by specifying the name of the class in the function prototype.

Példa 19-39. Type Hinting example

`<?php // An example class class MyClass { /** * A test function * * First parameter must be an object of type OtherClass */ public function test(OtherClass $otherclass) { echo $otherclass->var; } } // Another example class class OtherClass { public $var = 'Hello World'; } ?>`

Failing to satisfy the type hint results in a fatal error.

`<?php
// An instance of each class
$myclass = new MyClass;
$otherclass = new OtherClass;
// Fatal Error: Argument 1 must be an object of class OtherClass
$myclass->test('hello');
// Fatal Error: Argument 1 must be an instance of OtherClass
$foo = new stdClass;
$myclass->test($foo);
// Fatal Error: Argument 1 must not be null
$myclass->test(null);
// Works: Prints Hello World
$myclass->test($otherclass);
?>`

Type hinting also works with functions:

`<?php // An example class class MyClass { public $var = 'Hello World'; } /** * A test function * * First parameter must be an object of type MyClass */ function MyFunction (MyClass $foo) { echo $foo->var; } // Works $myclass = new MyClass; MyFunction($myclass); ?>`

Type Hints can only be of the object type. Traditional type hinting with int and string are not supported.

Előző | Tartalom | Következő
Reflection | Fel | Exceptions