PHP:从另一个文件调用父类

Question

我是 PHP 的新手。我了解 OOP 的概念，但在语法上，我不知道如何从另一个文件扩展父类。这是我的代码:

parent.php

<?php
namespace Animals;

class Animal{
    protected $name;
    protected $sound;
    public static $number_of_animals = 0;
    protected $id;

    public $favorite_food;

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

    function __construct(){
        $this->id = rand(100, 1000000);
        Animal::$number_of_animals ++;

    }

    public function __destruct(){

    }

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

    function __set($name, $value){
        switch($name){
            case 'name'     :
                $this->$name = $value;
                break;
            case 'sound'    :
                $this->$name = $value;
                break;
            case 'id'       :
                $this->$name = $value;
                break;
            default         :
                echo $name . " not found";
        }
    }

    function run(){
        echo $this->name . ' runs <br />';
    }

}
?>

extended-classes.php

<?php
namespace mammals;
include 'parent.php';

use Animals\Animal as Animal;

class Cheetah extends Animal{
    function __construct(){
        parent:: __construct(); 
    }
}



?>

ma​​in.php

<?php
include 'extended-classes.php';
include 'parent.php';

use Animals\Animal as Animal;
use mammals\Cheetah as Cheetah;

$cheetah_one = new Cheetah();

$cheetah_one->name = 'Blur';

echo "Hello! My name is " . $cheetah_one->getName();

?>

我正在使用 MAMP 运行代码，但不断出现以下错误:Cannot declare class Animals\Animal, because the name is already in use in/path/to/file/parent.php on第 4 行。感谢所有提示。

Answer 1

Main.php 不需要包含 parent.php，因为 extended-classes.php 已经包含了它。或者，您可以使用 include_once 或 require_once 而不是 include。