public function registerCallback($event, $callback)
    {
        $this->checkEventType($event);
        $this->events[$event][] = $callback;
    }
public function registerCallback($event, $callback)
    {
        $this->checkEventType($event);
        $this->events[$event][] = $callback;
    }
public function registerCallback ( $ event , $ callback ) { $ this -> checkEventType ( $ event ) ; $ this -> events [ $ event ] [ ] = $ callback ; }
Registers new callback for given event

@param string $event
@param mixed $callback
Registers new callback for given event