অবজার্ভার

<?php

class Model implements SplSubject
{
    protected $observers;

    public function __construct()
    {
        $this->observers = new SplObjectStorage();
    }

    public function attach(SplObserver $observer)
    {
        $this->observers->attach($observer);
    }

    public function detach(SplObserver $observer)
    {
        $this->observers->detach($observer);
    }

    public function notify()
    {
        foreach ($this->observers as $observer) {
            $observer->update($this);
        }
    }

    public function __set($name, $value)
    {
        $this->data[$name] = $value;
        // notify the observers, that model has been updated
        $this->notify();
    }
}

class ModelObserver implements SplObserver
{
    public function update(SplSubject $subject)
    {
        echo get_class($subject) . ' has been updated' . '<br>';
    }
}

class Observer2 implements SplObserver
{
    public function update(SplSubject $subject)
    {
        echo get_class($subject) . ' has been updated' . '<br>';
    }
}

// Instantiate the model class for 2 different objects
$model1 = new Model();
$model2 = new Model();

// Instantiate the observers
$modelObserver = new ModelObserver();
$observer2 = new Observer2();

// Attach the observers to $model1
$model1->attach($modelObserver);
$model1->attach($observer2);

// Attach the observers to $model2
$model2->attach($observer2);

// Changing the subject properties
$model1->title = 'Hello World';
$model2->body = 'Lorem ipsum............';