Question

I’ve been making several libraries and extension libraries, and it’s not practical for me to use prototype because in the real-world you actually have private variables that do not need to be accessed from an instantiated object.

var parent_class = function(num) {
    var number = num;

    this.method = function(anum) {
        number += anum;
    };
    this.getNumber = function() {
        var fnumber = number + 2;
        return fnumber;
    };
};

var child_class = function(num1, num2) {
    var sum = num1 + num2;
    parent_class.call(this, sum); // initialize parent class

    this.method = function() {
        sum -= 1;
        base.method(sum); // what to do here
    };
};

child_class.prototype = new parent_class(); // inherit from parent
child_class.prototype.constructor = child_class; // maintain new constructor

var c = new child_class(1, 4); // child_class.sum = 5, parent_class.number = 5
c.method(); // child_class.sum = 4, parent_class.number = 9
var num = c.getNumber(); // returns 11

Now, without declaring and relying on methods being prototyped, how can I get the what to do here line to work? I understand that I could call this.method(); inside child_class and store it as a variable, but I want overridable methods.

My previous topic was not very forthcoming, as everyone assumes I can just prototype everything or use private variables to get around the problem. There has to be a way to do this without prototyping.

I want to call .method(); from inside an instance of child_class without storing the previous .method(); as a private variable or using prototype methods that, for obvious reasons, cannot access private members.

Answer 1

Just use the prototype, you can mark “private” properties and methods with NULL character prefix or whatever to discourage people from using them, which is all you really need.

MyClass.prototype = {

    "\0privateMethod": function(){}

};

If you’re using chrome you will see this in console:

Object
privateMethod: function (){}
__proto__: Object

Yet one cannot do myClass.privateMethod(), this should be enough of a hint that this is a private property. To actually call it, you’d need to write myClass["\0privateMethod"]().

After going back to using prototype, your problem should automatically become easy to solve.