//============================ class KillBot implements SplObserver { public function update(SplSubject $subject) { echo __CLASS__ . " says kill all humans." . PHP_EOL; } } class LoveBot implements SplObserver { public function update(SplSubject $subject) { echo __CLASS__ . " says kiss all humans." . PHP_EOL; } } // load the observable (SPLSubject) $robots = new Observable(); // load some observers $killbot = new KillBot(); $lovebot = new LoveBot(); // add the observers to the observable $robots->addObserver($killbot); $robots->addObserver($lovebot); // notify the observers of an event $robots->notify(); /* Observers output: KillBot says kill all humans LoveBot says kiss all humans */