如何在JavaScript中创建受保护的对象属性

问题描述

是否存在模仿受保护对象属性的JavaScript模式，就像您在C ++等语言中看到的那样？

Is there a JavaScript pattern which mimics "Protected" object properties like what you see in languages like C++ ??

基本上，我想创建一个Object A具有许多受保护对象属性，只能从对象A的原型中定义的方法访问。即 - 不能从A的非原型方法公开访问。

Basically, I'd like to create an Object A which has a number of "protected" object properties which can be accessed ONLY from methods which are defined from the prototype of Object A. i.e. - NOT accessible publicly from non-prototyped methods of A.

例如，理想情况是这样的：

For instance, ideally would be like so:

function A(){
    var prop1 = 1;
}

A.prototype.myFunc = function(){
    var newVar = this.prop1;   //newVar now is equivalent to 1
}

var instanceOfA = new A();
var newVar2 = instanceOfA.prop1;  //error given as prop1 is "protected"; hence undefined in this case

BTW - 我不希望特权成员函数的模式访问私有属性成员函数仍然是公共的。

BTW - I do not want the pattern of privileged member functions accessing private properties since the member function is still public.

推荐答案

没有对象属性只能从<$ c $的原型方法中访问c> A 而不是来自 A 的非原型方法。该语言没有这种类型的功能，我不知道任何解决方法/黑客实现它。

There is no object property that can only be accessed from prototyped methods of A and not from non-prototyped methods of A. The language doesn't have that type of feature and I'm not aware of any work-around/hack to implement it.

使用，您可以创建成员属性只能从预定义的非原型方法（在构造函数中定义的方法）访问。因此，如果您尝试仅限制对一组预定义方法的访问，则可以实现此目的。除此之外，我认为你运气不好。

Using Doug Crockford's methods, you can create member properties that can only be accessed from predefined non-prototyped methods (those defined in the constructor). So, if you're trying to limit access only to a predefined set of methods, this will accomplish that. Other than that, I think you're out of luck.

如果你想要其他想法，如果你描述的更多是关于你的想法，你可能会得到更多的帮助实际上试图在你的代码中完成，而不仅仅是如何用另一种语言模拟一个功能。 Javascript与C ++有很大的不同，最好从问题的需要开始，而不是试图找到一些C ++特性的类比。

If you want other ideas, you'd probably get more help if you describe more about what you're actually trying to accomplish in your code rather than just how to emulate a feature in another language. Javascript is so much different than C++ that it's better to start from the needs of the problem rather than try to find an analogy to some C++ feature.

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