Passing defined methods/functions (sort of)

gistfile1.php

<?php
class Mediator {
    private $events;

    public function attach($event, Callable $callback) {
        if (!isset($this->events[$event])) {
            $this->events[$events] = array();
        }
        $this->events[$event][] = $callback;
    }

    public function trigger($event) {
        if (isset($this->events[$event])) {
            foreach ($this->events[$event] as $func) {
                $func();
            }
        }
    }
}

class DefinesSomething {
    public function attachTo(Mediator $m) {
        $m->attach('event', function () use ($this) {
            $this->event();
        });
    }
    
    public function event() {
        echo "Event triggered\n";
    }
}

$ds = new DefinesSomething;
$m = new Mediator;
$ds->attachTo($m);

$m->trigger('event');
?>