Is it possible to specify more than one type hint for a parameter? [duplicate]

Question

Is there a way to add more than one type hinting to a method? For example, foo(param) must receive a instance of string OR bar OR baz.

Answer 1

That is not possible to enforce (except inside the method). You can only provide a single type hint, and only to objects/interfaces and arrays (since PHP 5.1).

You can/should however document it in your method, i.e:

/**
 * @param string|Bar|Baz $param1
 */
function foo($param1);

Answer 2

This is one use of interfaces. If you want to be sure that the object has a ->foobar($baz) method, you could expect an interface:

interface iFooBar {
    public function foobar($baz);
}

class Foo implements iFooBar {
    public function foobar($baz) { echo $baz; }
}
class Bar implements iFooBar {
    public function foobar($baz) { print_r($baz); }
}

function doSomething(iFooBar $foo) {
    $foo->foobar('something');
}

Then, when calling, these will work:

doSomething(new Foo());
doSomething(new Bar());

These will not:

doSomething(new StdClass());
doSomething('testing');