php – 在父类中使用$this仅在子类中显示父类属性

2023年1月5日 228次阅读

我有以下两个班级. BMW级延伸级轿车.

class Car{

    public $doors;
    public $wheels;
    public $color;
    public $size;

    public function print_this(){
        print_r($this);
    }

}

class BMW extends Car{
    public $company;
    public $modal;

    public function __construct(){
        print_r(parent::print_this());
    }
}

$bmw = new BMW();
$bmw->print_this();

在上面的代码中,当我使用parent :: print_this()和内部print_this()方法从构造函数访问父类方法时,我有print_r($this),它打印所有属性(父类和子类属性)
现在我想要print_r(parent :: print_this());应该只输出子类中的父类属性？谁可以帮我这个事？

最佳答案 您可以使用
reflection实现此目的：

class Car{
    public $doors;
    public $wheels;
    public $color;
    public $size;

    public function print_this(){
        $class = new ReflectionClass(self::class); //::class works since PHP 5.5+

        // gives only this classe's properties, even when called from a child:
        print_r($class->getProperties());
    }
}

您甚至可以从子类反映到父类：

class BMW extends Car{
    public $company;
    public $modal;

    public function __construct(){
        $class = new ReflectionClass(self::class);
        $parent = $class->getParentClass();
        print_r($parent->getProperties());
    }
}

编辑：

what actually I want that whenever I access print_this() method using object of class BMW it should print BMW class properties only and when I access print_this() from BMW class using parent it should print only parent class properties.

有两种方法可以使相同的方法表现不同：在子类中重写它或者将其重载/传递给它.因为重写它会意味着很多代码重复(你必须在每个子类中基本相同)我建议你在父Car类上构建print_this()方法,如下所示：

public function print_this($reflectSelf = false) {
    // make use of the late static binding goodness
    $reflectionClass = $reflectSelf ? self::class : get_called_class();
    $class = new ReflectionClass($reflectionClass);

    // filter only the calling class properties
    $properties = array_filter(
        $class->getProperties(), 
        function($property) use($class) { 
           return $property->getDeclaringClass()->getName() == $class->getName();
    });

    print_r($properties);
}

现在,如果您明确要从子类打印父类属性,只需将标志传递给print_this()函数：

class BMW extends Car{
    public $company;
    public $modal;

    public function __construct(){
        parent::print_this(); // get only this classe's properties
        parent::print_this(true); // get only the parent classe's properties
    }
}
点赞