设计模式-装饰者模式

<?php

/**
 * 装饰者模式
 * 动态的为对象增加职责
 */
interface Drink {

    public function cost();
}

class Coffee implements Drink {

    public function cost() {
        return 10;
    }

}

abstract class Drink_Decorator implements Drink {

    protected $drink;

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

}

class Sugar extends Drink_Decorator {

    public function cost() {
        return $this->drink->cost() + 6;
    }

}

class Milk extends Drink_Decorator {

    public function cost() {
        return $this->drink->cost() + 7;
    }

}

$coffee = new Coffee();


$coffee = new Sugar($coffee);

$coffee = new Milk($coffee);

echo $coffee->cost();