PHP 객체지향 다형성에 대한 자세한 설명(코드 예)

<?php
//定义吃的接口
interface Eat{
    public function eat();
}
//定义猫的类
class Cat implements Eat{
    public function eat(){
        echo "我是猫，抓到喜欢的老鼠，直接吃<br/>";
    }
}
//定义人
class Human implements Eat{
    public function eat(){
        echo "我是人，吃东西之前，都会洗一下再吃，因为我要讲究基本的卫生<br/>";
    }
}

function Eat( $obj ){
    if( $obj instanceof Eat ){
        $obj->eat();
    }else{
        echo "该对象没有实现Eat的方法<br/>";
    }
}
$cat = new Cat();
$zs = new Human();
//这行代码看出，一个吃的方法，传递不同的具体实现，结果就是可以有不同的实现，这就是多态
Eat($cat);
Eat($zs);
?>

<?php
//定义吃的接口
interface Eat{
    public function eat($food);
}
//定义食物
class Food{
    public $name = "";
    public function __construct( $name ){
        $this->name = $name;
    }
}

//定义人
class Human implements Eat{
    public $name = "";
    public function __construct( $name ){
        $this->name = $name;
    }
    //起床
    public function wakeup(){
        echo $this->name."起床了<br/>";
    }
    //煮稀饭
    public function cook($food){
        echo $this->name."煮".$food->name."了<br/>";
    }
    public function eat($food){
        echo $this->name."吃了".$food->name."<br/>";
    }
    //喂食
    function startFeed( $obj,$food ){
        if( $obj instanceof Eat ){
            $obj->eat($food);
        }else{
            echo "该对象没有实现Eat的方法<br/>";
        }
    }

    public function feed($obj, $food){
        $this->startFeed( $obj,$food );
    }
}
//定义鸡的类
class Chiken implements Eat{
    public $count = 5;
    public function eat($food){
        echo $this->count."只小鸡们，都吃了".$food->name."<br/>";
    }
}
//定义狗的类
class Dog implements Eat{
    public $count = 5;
    public function eat($food){
        echo $this->count."只小狗们，都吃了".$food->name."<br/>";
    }
}

//创建对象
$xiaoliu = new Human("小刘");
$chikens = new Chiken();
$dogs = new Dog();
//创建食物
$xfFood = new Food("稀饭");
$seedsFood = new Food("米");
$mealFood = new Food("残羹剩饭");
//老人起床
$xiaoliu->wakeup();
//老人煮稀饭
$xiaoliu->cook($xfFood);
//老人吃稀饭
$xiaoliu->eat( $xfFood );
//老人喂食开始
$xiaoliu->feed($chikens,$seedsFood);//给小鸡喂食
$xiaoliu->feed($dogs,$mealFood);//给小狗喂食

?>