Was bedeutet Polymorphismus in PHP?

class painter{ //定义油漆工类
public function paintbrush(){ //定义油漆工动作
echo "油漆工正在刷漆！\n";
}
}
class typist{ //定义打字员类
public function typed(){ //定义打字员工作
echo "打字员正在打字！\n";
}
}
function printworking($obj){ //定义处理类
if(objinstanceofpainter)//若对象是油漆工类，则显示油漆工动作$obj−>paintbrush();elseif(obj instanceof typist){ //若对象是打字员类，则显示打字员动作
$obj->typed();
}else{ //若非以上类，则显示出错信息
echo "Error: 对象错误！";
}
}
printworking(new painter()); //显示员工工作
printworking(new typist()); //显示员工工作

油漆工正在刷漆  
打字员正在打字

class employee{//定义员工父类
protected function working(){//定义员工工作，需要在子类的实现
echo "本方法需要在子类中重载!";
}
}
class painter extends employee{//定义油漆工类
public function working(){//实现继承的工作方法
echo "油漆工正在刷漆！\n";
}
}
class typist extends employee{//定义打字员类
public function working(){
echo "打字员正在打字！\n";
}
}
class manager extends employee{//定义经理类
public function working(){
echo "经理正在开会！";
}
}
function printworking($obj){//定义处理方法
if($obj instanceof employee){//若是员工对象，则显示其工作状态
$obj->working();
}else{//否则显示错误信息
echo "Error: 对象错误！";
}
}
printworking(new painter());//显示油漆工的工作
printworking(new typist());//显示打字员的工作
printworking(new manager());//显示经理的工作

油漆工正在刷漆! 
打字员正在打字! 
经理正在开会!

<?php
interface User{ // User接口
    public function  getName();
    public function setName($_name);
}
class NormalUser implements User { // 实现接口的类.
    private $name;
    public function getName(){
        return $this->name;
    }
    public function setName($_name){
        $this->name = $_name;
    }
}
class UserAdmin{ //操作.
    public 
static
 function  ChangeUserName(User $_user,$_userName){
        $_user->setName($_userName);
    }
}
$normalUser = new NormalUser();
UserAdmin::ChangeUserName($normalUser,"Tom");//这里传入的是 NormalUser的实例.
echo $normalUser->getName();
?>

<?php
interface User
{
    public function getName();
    public function setName($_name);
    public function getDiscount();
}
abstract class AbstractUser implements User
{
    private $name = "";
    protected  $discount = 0;
    protected  $grade = "";
    function construct($_name) {
        $this->setName($_name); 
    }
    function getName() {
        return $this->name;
    }
    function setName($_name) {
    $this->name = $_name;
    }
    function getDiscount() {
        return $this->discount;
    }
    function getGrade() {
        return $this->grade;
    }
}
class NormalUser 
extends
 AbstractUser
{
    protected $discount = 1.0;
    protected $grade = "Normal";
}
class VipUser extends AbstractUser
{
    protected $discount = 0.8;
    protected $grade = "VipUser";
}
class InnerUser extends AbstractUser
{
    protected $discount = 0.7;
    protected $grade = "InnerUser";
}
interface Product
{
    function getProductName();
    function getProductPrice();
}
interface Book extends Product
{
    function getAuthor();
}
class BookOnline implements Book
{
    private $productName;
    protected $productPrice;
    protected $Author;
    function construct($_bookName) {
        $this->productName = $_bookName;
    }
    function getProductName() {
        return $this->productName;
    }
    function getProductPrice() {
        $this->productPrice = 100;
        return $this->productPrice;
    }
    public function getAuthor() {
        $this->Author = "chenfei";
        return $this->Author;
    }
}
class Productsettle
{
    public static function finalPrice(User $_user, Product $_product, $number) {
        $price = $_user->getDiscount() * $_product->getProductPrice() * $number;
        return $price;
    }
}
$number = 10;
$book = new BookOnline("
设计模式
");
$user = new NormalUser("tom");
$price = Productsettle::finalPrice($user, $book, $number);
$str = "您好，尊敬的" . $user->getName() . "<br />";
$str .= "您的级别是" . $user->getGrade() . "<br />";
$str .= "您的折扣是" . $user->getDiscount() . "<br />";
$str .= "您的价格是" . $price;
echo $str;
?>