PHP Manual by the PHP Documentation Group php.net
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.
Example 19-42. 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.
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