<?php require_once 'observer.php'; require_once 'subject.php'; require_once 'concreteSubject.php'; require_once 'observerA.php'; require_once 'observerB.php'; $subject = new ConcreteSubject(); $observerA = new ObserverA(); $observerB = new ObserverB(); $subject->registerObserver($observerA); $subject->registerObserver($observerB); $subject->setValue(5);