PHP Observer Pattern in Laravel Framework

This article mainly introduces the PHP observer mode, and analyzes the simple definition and usage techniques of the PHP observer mode in the form of examples. Friends in need can refer to it

The examples in this article describe the PHP observer model. Share it with everyone for your reference, the details are as follows:

<?php
//观察者模式
//抽象主题类
interface Subject
{
  public function attach(Observer $Observer);
  public function detach(Observer $observer);
  //通知所有注册过的观察者对象
  public function notifyObservers();
}
//具体主题角色
class ConcreteSubject implements Subject
{
  private $_observers;
  public function __construct()
  {
    $this->_observers = array();
  }
  //增加一个观察者对象
  public function attach(Observer $observer)
  {
    return array_push($this->_observers,$observer);
  }
  //删除一个已经注册过的观察者对象
  public function detach(Observer $observer)
  {
    $index = array_search($observer,$this->_observers);
    if($index === false || !array_key_exists($index, $this->_observers)) return false;
    unset($this->_observers[$index]);
    return true;
  }
  //通知所有注册过的观察者
  public function notifyObservers()
  {
    if(!is_array($this->_observers)) return false;
    foreach($this->_observers as $observer)
    {
      $observer->update();
    }
    return true;
  }
}
//抽象观察者角色
interface Observer
{
  //更新方法
  public function update();
}
//观察者实现
class ConcreteObserver implements Observer
{
  private $_name;
  public function __construct($name)
  {
    $this->_name = $name;
  }
  //更新方法
  public function update()
  {
    echo &#39;Observer&#39;.$this->_name.&#39; has notify&#39;;
  }
}
$Subject = new ConcreteSubject();
//添加第一个观察者
$observer1 = new ConcreteObserver(&#39;baixiaoshi&#39;);
$Subject->attach($observer1);
echo &#39;the first notify:&#39;;
$Subject->notifyObservers();
//添加第二个观察者
$observer2 = new ConcreteObserver(&#39;hurong&#39;);
echo &#39;<br/>second notify:&#39;;
$Subject->attach($observer2);
/*echo $Subject->notifyObservers();
echo &#39;<br/>&#39;;
$Subject->notifyObservers();*/
?>

Running results:

the first notify:Observerbaixiaoshi has notify
second notify:

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