17.php模版模式

    直接上代码。

<?phpabstract class sale{    public $price = 0;        public final function setprice(){        $this->price += $this->Tax();        $this->price -= $this->sale();    }        //税务    protected function Tax(){        return 0;    }        //租金    protected abstract function sale(); }class Book extends sale{    public $name;    public $author;        function __construct($name, $author, $price){        $this->name = $name;        $this->author = $author;        $this->price = $price;    }        function sale(){        return $this->price*0.1;    }}$book = new Book('《夜航西飞》', "马卡姆 柏瑞尔",100);$book->setprice();echo $book->price;