Question

<?php

class FirstClass{
    public static $second;  
    public static $result = 'not this =/';
    public function __construct(){
        $this->result = 'ok';
        $this->second = new SecondClass();
    }   

    public function show(){
        echo $this->second->value;
    }
}

class SecondClass extends FirstClass{
    public $value;
    public function __construct(){
        $this->value = parent::$result; //Make it get "ok" here
    }
}

$temp = new FirstClass();
$temp->show(); //It will show: "not this =/"

?>

如何打印“ok”？

我的意思是，SecondClass应该知道FirstClass设置的结果，参见？

Answer 1

将$this->result = 'ok';替换为self::$result = 'ok';构造函数中的FirstClass。

是的，代码太可怕了。您正在混合静态和实例变量，并扩展类但不使用福利扩展提供。

Answer 2

你需要在第一个类中引用static作为self :: $结果。

下面应该做你想要的......

<?php

class FirstClass{
    public static $second;  
    public static $result = 'not this =/';
    public function __construct(){
        self::$result = 'ok';
        $this->second = new SecondClass();
    }   

    public function show(){
        echo $this->second->value;
    }
}

class SecondClass extends FirstClass{
    public $value;
    public function __construct(){
        $this->value = parent::$result; //Make it get "ok" here
    }
}

$temp = new FirstClass();
$temp->show(); //It will show: "not this =/"

?>

Php类 - 如何使类知道父值

2 个答案: