Calling closure assigned to object property directly

As of PHP7, you can do

$obj = new StdClass;$obj->fn = function($arg) { return "Hello $arg"; };echo ($obj->fn)('World');

or use Closure::call(), though that doesn't work on a StdClass.

Before PHP7, you'd have to implement the magic __call method to intercept the call and invoke the callback (which is not possible for StdClass of course, because you cannot add the __call method)

class Foo{    public function __call($method, $args)    {        if(is_callable(array($this, $method))) {            return call_user_func_array($this->$method, $args);        }        // else throw exception    }}$foo = new Foo;$foo->cb = function($who) { return "Hello $who"; };echo $foo->cb('World');

Note that you cannot do

return call_user_func_array(array($this, $method), $args);

in the __call body, because this would trigger __call in an infinite loop.

You can do this by calling __invoke on the closure, since that's the magic method that objects use to behave like functions:

$obj = new stdClass();$obj->callback = function() {    print "HelloWorld!";};$obj->callback->__invoke();

Of course that won't work if the callback is an array or a string (which can also be valid callbacks in PHP) - just for closures and other objects with __invoke behavior.

As of PHP 7 you can do the following:

($obj->callback)();