装饰器模式

<?php 
abstract class Component {
  abstract public function operation();
}

class MyComponent extends Component
{
  public function operation()
  {
      echo "这是正常的组件方法 <br>";
  }
}

abstract class Decorator extends Component {
  protected $component;
  function __construct(Component $component)
  {
      $this->component = $component;
  }

  public function operation()
  {
      $this->component->operation();
  }
}

class MyDecorator extends Decorator
{

  function __construct(Component $component)
  {
      parent::__construct($component);
  }

  public function addMethod()
  {
      echo "这是装饰器添加的方法 <br>";
  }

  public function operation()
  {
      $this->addMethod();
      parent::operation();
  }
}

$component = new MyComponent();
$da = new MyDecorator($component);
$da->operation();