从孩子访问父类的属性 [英] Accessing Parent Class' property from child

问题描述

请参见以下示例(PHP)

See the following example (PHP)

class Parent
{ 
  protected $_property;
  protected $_anotherP;

  public function __construct($var)
  {
    $this->_property = $var;
    $this->someMethod();  #Sets $_anotherP
  }

  protected function someMethod()
  ...
}

class Child extends Parent
{
  protected $parent;

  public function __construct($parent)
  {
    $this->parent = $parent;
  }

  private function myMethod()
  {
    return $this->parent->_anotherP;  #Note this line
  }
}

我是OOP的新手，有点无知.

I am new to OOP and am a bit ignorant.

这里我使用的是该类的实例来访问parents属性，这似乎是错误的:S(然后不需要成为i的孩子).有没有一种简单的方法，这样我就可以将父属性与子属性同步，并且可以直接访问$ this-> otherotherP，而不必使用$ this-> parent-> anotherP吗?

Here to access the parents property I am using an instance of that class, which seems wrong :S (no need of being i child then). Is there an easy way, so that i can sync the parent properties with the child properties and can directly access $this->anotherP without having to use $this->parent->anotherP ?

推荐答案

随着您的Child类扩展Parent类，Parent中public或protected的每个属性和方法Child类将看到该类，就像它们是在Child类中定义的一样-反之亦然.

As your Child class is extending your Parent class, every properties and methods that are either public or protected in the Parent class will be seen by the Child class as if they were defined in the Child class -- and the other way arround.

当Child类extends Parent类时，可以将其视为"Child是Parent" -这表示Child具有Parent的属性，除非它以另一种方式重新定义了它们.

When the Child class extends the Parent class, it can be seen as "Child is a Parent" -- which means the Child has the properties of the Parent, unless it redefines those another way.

(顺便说一句，请注意，"parent"是PHP中的保留关键字，这意味着您不能使用该名称来命名一个类)

(BTW, note that "parent" is a reserved keyword, in PHP -- which means you can't name a class with that name)

这是父"类的简单示例:

Here's a quick example of a "parent" class :

class MyParent {
    protected $data;
    public function __construct() {
        $this->someMethodInTheParentClass();
    }
    protected function someMethodInTheParentClass() {
        $this->data = 123456;
    }
}

这是子"类:

class Child extends MyParent {
    public function __construct() {
        parent::__construct();
    }
    public function getData() {
        return $this->data; // will return the $data property 
                            // that's defined in the MyParent class
    }
}

可以通过这种方式使用:

That can be used this way :

$a = new Child();
var_dump($a->getData());

然后您将得到输出:

int 123456

这意味着$data属性是在MyParent类中定义的，并且是在同一MyParent类的方法中初始化的，因此Child类可以访问它，就像它是自己的一样.

Which means the $data property, defined in the MyParent class, and initialized in a method of that same MyParent class, is accessible by the Child class as if it were its own.

为了简单起见:由于Child是" MyParent，它不需要保持指向...本身的指针；-)

To make things simple : as the Child "is a" MyParent, it doesn't need to keep a pointer to... itself ;-)

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