装饰器模式

<?php
class baseart{
    public $content;
    protected $art = null;
    public function __construct($content){
        $this->content = $content;
    }
    public function decorator(){
        return $this->content;
    }
}

//编辑文章
class bianart extends baseart{
    public function __construct(baseart $art){
        $this->art = $art;
    }
    public function decorator(){
        return $this->content = $this->art->decorator()."--小编摘要--";
    }
}

//编辑文章
class seoart extends baseart{
    public function __construct(baseart $art){
        $this->art = $art;
    }
    public function decorator(){
        return $this->content = "--seo--".$this->art->decorator();
    }
}

$b = new seoart(new bianart(new baseart("天天向上")));
echo $b->decorator();

　　

另外一个例子：

<?php

/**
 * Class Component
 * Component抽象类, 可以给这些对象动态的添加职责
 */
abstract class Component
{
    abstract public function operation();
}


/**
 * Component的实现类
 * Class ConcreteComponent
 */
class ConcreteComponent extends Component
{
    public function operation()
    {
        echo __CLASS__ .  '|' . __METHOD__ . "
";
    }
}


/**
 * Class Decorator
 * 装饰器的抽象类，维持一个指向组件对象的接口对象， 并定义一个与组件接口一致的接口
 */
abstract class Decorator extends Component
{
    /**
     * 持有Component的对象
     */
    protected $component;

    /**
     * 构造方法传入
     */
    public function __construct(Component $component)
    {
        $this->component = $component;
    }

    abstract public function operation();
}

/**
 * Class ConcreteDecoratorA
 * 装饰器的具体实现类，向组件对象添加职责，beforeOperation()，afterOperation()为前后添加的职责。
 */
class ConcreteDecoratorA extends Decorator
{
    //在调用父类的operation方法的前置操作
    public function beforeOperation()
    {
        echo __CLASS__ . '|' . __METHOD__ . "
";
    }

    //在调用父类的operation方法的后置操作
    public function afterOperation()
    {
        echo __CLASS__ . '|' . __METHOD__ . "
";
    }

    public function operation()
    {
        $this->beforeOperation();
        $this->component->operation();//这里可以选择性的调用父类的方法，如果不调用则相当于完全改写了方法，实现了新的功能
        $this->afterOperation();
    }
}

class ConcreteDecoratorB extends Decorator
{
    //在调用父类的operation方法的前置操作
    public function beforeOperation()
    {
        echo __CLASS__ . '|' . __METHOD__ . "
";
    }

    //在调用父类的operation方法的后置操作
    public function afterOperation()
    {
        echo __CLASS__ . '|' . __METHOD__ . "
";
    }

    public function operation()
    {
        $this->beforeOperation();
        $this->component->operation();//这里可以选择性的调用父类的方法，如果不调用则相当于完全改写了方法，实现了新的功能
        $this->afterOperation();
    }
}

//客户端使用装饰器
$component = new ConcreteComponent();
$decoratorA = new ConcreteDecoratorA($component);
$decoratorB = new ConcreteDecoratorB($decoratorA);
$decoratorB->operation();

ConcreteDecoratorB|ConcreteDecoratorB::beforeOperation
ConcreteDecoratorA|ConcreteDecoratorA::beforeOperation
ConcreteComponent|ConcreteComponent::operation
ConcreteDecoratorA|ConcreteDecoratorA::afterOperation
ConcreteDecoratorB|ConcreteDecoratorB::afterOperation