PHP面向对象开发之类中接口的应用(interface、implements)

interface demo {
const NAME = "常量对象属性";

function fun1();
function fun2(); //抽象方法。
}

interface demo {
 const NAME = "名称";
 function fun1();
 function fun2();
}

interface demo2 {
 function fun3();
 function fun4();
}

interface demo3 {
 const TEST = "Test";
 function fun5();
}

class MyPc implements demo, demo2 {
 function fun1() {
  echo "++++++++++
";
 }
 function fun2() {
  echo "----------
";
 }
 function fun3() {
  echo "1111111111
";
 }
 function fun4() {
  echo "2222222222
";
 }
}

class MyPs extends MyPc implements demo3 {
 function fun5() {
  echo "继承类后引用接口";
 }
}
$p = new MyPs;
$p->fun1();
$p->fun2();
$p->fun3();
$p->fun4();
$p->fun5();
?>

//定义接口
interface User{
    function getDiscount();
    function getUserType();
}
//VIP用户 接口实现
class VipUser implements User{
    // VIP 用户折扣系数
    private $discount = 0.8;
    function getDiscount() {
        return $this->discount;
    }
    function getUserType() {
        return "VIP用户";
    }
}
class Goods{
    var $price = 100;
    var $vc;
    //定义 User 接口类型参数，这时并不知道是什么用户
    function run(User $vc){
        $this->vc = $vc;
        $discount = $this->vc->getDiscount();
 $usertype = $this->vc->getUserType();
        echo $usertype."商品价格：".$this->price*$discount;
    }
}

$display = new Goods();
$display ->run(new VipUser); //可以是更多其他用户类型
?>