callable_typehint_not_directly_callable.md

Callable type-hint not directly callable

NOTE: This has been fixed in PHP-7

Arguments marked with the callable type-hint aren't directly callable because a string to a static method "Class::method" will be interpreted as a normal function.

To resolve that, you have to call call_user_func[_array]().

Example:

(http://3v4l.org/rGc3F)

class Foo {
    public static function bar() {
        return __METHOD__;
    }
}

function call(callable $func) {
    return $func();
}

// works
$callable = array('Foo', 'bar');
var_dump($callable());
var_dump(call($callable));

// Call to undefined function Foo::bar()
$callable = 'Foo::bar';
var_dump(call($callable)); // or var_dump($callable());

string(8) "Foo::bar"
string(8) "Foo::bar"

Fatal error: Call to undefined function Foo::bar() in ... on line 10

Note the message ... undefined function .... On calling an undefined static method the message will be ... undefined method ....