Detailed code explanation of PHP's native support for the observer pattern

storage = new SplObjectStorage(); } public function attach(SplObserver $obs) { $this->storage->attach($obs); } public function detach(SplObserver $obs) { $this->storage->detach($obs); } public function notify() { foreach($this->storage as $ol) { $ol->update($this); } } public function doAct() { echo 'DoAct ... 
'; $this->notify(); } } /** * concrete observer 1 */ class Observer1 implements SplObserver { public function update(SplSubject $sub) { echo 'Observer one updated! 
'; } } /** * concrete observer 2 */ class Observer2 implements SplObserver { public function update(SplSubject $sub) { echo 'Observer two updated! 
'; } } // test code $sub = new ConcreteSubject(); $sub->attach(new Observer1()); //add observer $sub->attach(new Observer1()); $sub->attach(new Observer2()); $sub->doAct();