php 函数或者方法预设接口类型 运行时类型检查

<?php
interface IUser 
{ 
	function getName(); 
	function setName($_name); 
	function getDiscount(); //此处添加了一个抽象的方法
} 

 
class VipUser implements IUser 
{ 
	private $name; 
	private $discount = 0.8; //折扣变量 

	function getName() { 
		return $this->name; 
	} 

	function setName($_name) { 
		$this->name = $_name; 
	} 
	function getDiscount() { 
		return $this->discount; 
	} 

} 

class GoodUser implements IUser 
{ 
	private $name; 
	private $discount = 0.7; //折扣变量 

	function getName() { 
		return $this->name; 
	} 

	function setName($_name) { 
		$this->name = $_name; 
	} 
	function getDiscount() { 
		return $this->discount; 
	} 

} 


error_reporting(-1);
$v = new VipUser;
$g=new GoodUser;
//echo $v->getDiscount();

 

test($v);//ok
test($g);//ok
test("d");// error !;Catchable fatal error: Argument 1 passed to test() must implement interface IUser, string given, 

function test(IUser $p)
{
	echo $p->getDiscount();

}