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) or arrays (since PHP 5.1). However, if NULL is used
as the default parameter value, it will be allowed as an argument for any
later call.
Type Hinting examples
var;
}
/**
* Another test function
*
* First parameter must be an array
*/
public function test_array(array $input_array) {
print_r($input_array);
}
}
// Another example class
class OtherClass {
public $var = 'Hello World';
}
?>
]]>
Failing to satisfy the type hint results in a catchable fatal error.
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);
// Fatal Error: Argument 1 must be an array
$myclass->test_array('a string');
// Works: Prints the array
$myclass->test_array(array('a', 'b', 'c'));
?>
]]>
Type hinting also works with functions:
var;
}
// Works
$myclass = new MyClass;
MyFunction($myclass);
?>
]]>
Type hinting allowing NULL value:
]]>
Type Hints can only be of the object and array
(since PHP 5.1) type. Traditional type hinting with int and
string isn't supported.