[英]How to inherit a private member in JavaScript?
is there a way in JavaScript to inherit private members from a base class to a sub class? 在JavaScript中有一种方法可以将私有成员从基类继承到子类吗?
I want to achieve something like this: 我希望实现这样的目标:
function BaseClass() {
var privateProperty = "private";
this.publicProperty = "public";
}
SubClass.prototype = new BaseClass();
SubClass.prototype.constructor = SubClass;
function SubClass() {
alert( this.publicProperty ); // This works perfectly well
alert( this.privateProperty ); // This doesn't work, because the property is not inherited
}
How can I achieve a class-like simulation, like in other oop-languages (eg. C++) where I can inherit private (protected) properties? 我怎样才能实现类似于类的模拟,就像我可以继承私有(受保护)属性的其他oop语言(例如C ++)一样?
Thank you, David Schreiber 谢谢David Schreiber
Using Douglas Crockfords power constructor pattern (link is to a video), you can achieve protected variables like this: 使用Douglas Crockfords电源构造函数模式 (链接到视频),您可以实现这样的受保护变量:
function baseclass(secret) {
secret = secret || {};
secret.privateProperty = "private";
return {
publicProperty: "public"
};
}
function subclass() {
var secret = {}, self = baseclass(secret);
alert(self.publicProperty);
alert(secret.privateProperty);
return self;
}
Note: With the power constructor pattern, you don't use new
. 注意:使用电源构造函数模式,您不使用
new
。 Instead, just say var new_object = subclass();
相反,只需说
var new_object = subclass();
. 。
Mark your private variables with some kind of markup like a leading underscore _ This way you know it's a private variable (although technically it isn't) 使用某种标记(如前导下划线)标记您的私有变量_这样您就知道它是一个私有变量(虽然从技术上讲它不是)
this._privateProperty = "private";
alert( this._privateProperty )
This isn't possible. 这是不可能的。 And that isn't really a private property - it's simply a regular variable that's only available in the scope in which it was defined.
这不是一个真正的私有财产 - 它只是一个常规变量,只能在定义它的范围内使用。
That can't be done, but you could delete the property from the class prototype so that it is not inherited: 这是不可能的,但您可以从类原型中删除该属性,以便它不会被继承:
SubClass.prototype.privateProperty = undefined;
That way it won't be inherited, but you need to do that for every "private" property in your base class. 这样它就不会被继承,但你需要为你的基类中的每个“私有”属性做这件事。
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