PHP装饰者模式

装饰者模式

interface Beverage
{
	public function cost();
}

//被装饰
class Coffee implements Beverage
{
	public function cost()
	{
		return 1;
	} 
}

//装饰者
class CondimentDecorator implements Beverage
{
	public function cost()
	{

	}
}

class Milk extends CondimentDecorator
{	
	private $_beverage;
	public function __construct($beverage)
	{
		if($beverage instanceof Beverage) {
			$this->_beverage = $beverage;
		}
	}

	public function cost()
	{
		return $this->_beverage->cost() + 2;
	}
}

class Sugar extends CondimentDecorator
{
	private $_beverage;

	public function __construct($beverage)
	{
		if($beverage instanceof Beverage)
		{
			$this->_beverage = $beverage;
		}
	}

	public function cost()
	{
		return $this->_beverage->cost()+3;
	}
}

$coffee = new Coffee();
//加牛奶
$coffee = new Milk($coffee);
//加糖
$coffee = new Sugar($coffee);

//总消费
echo $coffee->cost();