如何在 oop PHP 中将参数传递给父构造函数？ [关闭]

Question

我正在尝试从一个基类实例化两个对象，并将一个参数从子类构造函数传递给父类构造函数。这似乎不起作用。就好像对象甚至不是父类的子对象一样。我不知道我做错了什么。

我已经尝试重新排列包含，不传递任何参数（这会导致错误，“需要一个参数”），以及其他修补都无济于事。

父类：

class SuperHero {
    private $health;
    private $name;
    private $isDead;

    public function __construct($name) {
        $this->name;
        $this->isDead = false;
    }

    // ...

    public function attack($opponent) { 
        echo $this->name.' attacks '.$opponent->name.'!<br>';
        $dmg = mt_rand(1, 10);
        $opponentHealth = determineHealth($opponent, $dmg);
        echo $opponent->name.' has '.$opponentHealth.' health left!<br>';
    }

    // ...

子类：

<?php
require_once('SuperHero.php');
class Batman extends SuperHero {

    public function __construct() {
        parent::__construct('Batman');
        $this->health = mt_rand(1, 1000);
    }

}

执行的脚本：

require_once('Batman.php');
require_once('Superman.php');

$h1 = new Batman;
$h2 = new Superman;

echo $h1->name.' is starting with '.$h1->health.' health!<br>';
echo $h2->name.' is starting with '.$h2->health.' health!<br>';

while($h1->getIsDead() == false && $h2->getIsDead() == false){    
    $h1->attack($h2);  
    $h2->attack($h1);
}

实际结果

is starting with 317 health!
Superman is starting with 300 health!
attacks !

预期结果

Batman is starting with 317 health!
Superman is starting with 300 health!
Batman attacks Superman!

Answer 1

你的父类的构造函数如下所示

public function __construct($name) {
    $this->name;
    $this->isDead = false;
}

$this->name; 单独什么都不做，它试图获取那个值。您需要通过执行

为其分配一个值

$this->name = $name;

那么，你所有的属性都是私有的，这意味着你不能通过$batman->name来访问它们。您需要为此实现一个 getter，$batman->getName()（对于您想要获取的每个属性）。如果它们是公开的，您可以通过 $batman->name 获取它们，但您也可以通过 $batman->name = 'Robin'; 覆盖它。最好使用 getter。

此外，determineHealth() 可能应该是类的方法并在 $opponent 对象上调用，而不是实际的函数。

class SuperHero {
    private $health;
    private $name;
    private $isDead;

    public function __construct($name, $health) {
        $this->name = $name;
        $this->health = $health;
        $this->isDead = false;
    }

    public function attack($opponent) { 
        $dmg = mt_rand(1, 10);
        echo $this->getName().' attacks '.$opponent->getName().' with '.$dmg." damage. ";
        $opponentHealth = $opponent->determineHealth($dmg);
        echo $opponent->getName().' has '.$opponentHealth." health left!<br />\n";
    }

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

    public function getHealth() {
        return $this->health;
    }

    public function isDead() {
        return $this->isDead;
    }

    public function determineHealth($health) {
        $this->health -= $health;
        if ($this->health <= 0) {
            $this->health = 0;
            $this->isDead = true;
        }
        return $this->health;
    }
}

class Batman extends SuperHero {
    public function __construct() {
        $health = mt_rand(1, 1000);
        parent::__construct('Batman', $health);
    }
}

class Superman extends SuperHero {
    public function __construct() {
        $health = mt_rand(1, 1000);
        parent::__construct('Superman', $health);
    }
}

$h1 = new Batman;
$h2 = new Superman;


echo $h1->getName().' is starting with '.$h1->getHealth()." health!<br>\n";
echo $h2->getName().' is starting with '.$h2->getHealth()." health!<br>\n";

$h1->attack($h2);  
$h2->attack($h1);

输出：

Batman is starting with 445 health!<br>
Superman is starting with 229 health!<br>
Batman attacks Superman with 5 damage. Superman has 224 health left!<br />
Superman attacks Batman with 9 damage. Batman has 436 health left!<br />

• https://3v4l.org/aDegT 现场演示

Answer 2

超类的name 和health 成员在子类中不可用，因为它们是私有的。

您应该将它们更改为 public 或者您应该创建公共 getter 和 setter 并使用它们。

Answer 3

私有变量不能被继承。

    <?php
class SuperHero {
    private $health;
    private $name;
    private $isDead;

    public function __construct($name) {
        $this->name = $name;
        $this->isDead = false;
    }

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

    public function attack($opponent) { 
        echo $this->name.' attacks '.$opponent->name.'!<br>';
        $dmg = mt_rand(1, 10);
        $opponentHealth = determineHealth($opponent, $dmg);
        echo $opponent->name.' has '.$opponentHealth.' health left!<br>';
    }
}

class Batman extends SuperHero {

    public function __construct() {
        parent::__construct('Batman');
        $this->health = mt_rand(1, 1000);
    }

}
class Superman extends SuperHero {

    public function __construct() {
        parent::__construct('Superman');
        $this->health = mt_rand(1, 1000);
    }

}

$h1 = new Batman;
$h2 = new Superman;

echo $h1->name().' is starting with '.$h1->health.' health!<br>';
echo $h2->name().' is starting with '.$h2->health.' health!<br>';

while($h1->getIsDead == false && $h2->getIsDead == false){    
    $h1->attack($h2);  
    $h2->attack($h1);
}

?>

在父类中 function name() 将返回从 parent::__construct('Name') 传递的名称。

输出

Batman is starting with 327 health!
Superman is starting with 842 health!
Batman attacks Superman!