php中的观察者模式简单实例_PHP教程

class DemoSubject implements SplSubject{
private $observers, $value;

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

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

public function detach(SplObserver $observer){
if($idx = array_search($observer, $this->observers, true)){
unset($this->observers[$idx]);
}
}

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

public function setValue($value){
$this->value = $value;
$this->notify();
}

public function getValue(){
return $this->value;
}
}

class DemoObserver implements SplObserver{
public function update(SplSubject $subject){
echo 'The new value is '. $subject->getValue();
}
}

$subject = new DemoSubject();
$observer = new DemoObserver();
$subject->attach($observer);
$subject->setValue(5);