How to Invoke Object that's a Public Property - php

Question

Take the following example of two classes:
class Yolo {
public function __invoke() {
echo 'YOLO';
}
}
class Swag {
public $yolo;
public function __construct() {
$this->yolo = new Yolo();
}
}
Is it possible to invoke the Yolo object via an instance of Swag?
(new Swag())->yolo(); throws a warning and doesn't call __invoke:
PHP Warning: Uncaught Error: Call to undefined method Swag::yolo()

Answer 1

In PHP 7 you can directly call it (just need extra braces):
((new Swag())->yolo)();
In PHP 5 you need a temp variable:
$y=(new Swag())->yolo;
$y();

Answer 2

The problem is that you try to call the function yolo() on the Swag class. In your case you have to use the public class variable and call the subclass over that.
var_dump((new Swag())->yolo);
that is your object. When you use () you try to call the class not the class variable.

Answer 3

You do not even have to make it a public method.
But you might have to reroute the call manually since the callable method is created at runtime:
class Yolo {
public function __invoke() {
echo 'YOLO';
}
}
class Swag {
private $yolo;
public function __construct() {
$this->yolo = new Yolo();
}
function __call($method, $args) {
if(is_callable($this->$method))
{
return call_user_func_array($this->$method, $args);
}
}
}
(new Swag())->yolo();
It would probably a good idea to check first, if the called method exists and if it is actually callable.
But the example works as a proof of concept.