Question

I want to achieve a syntax similar to this one using JS setters and getters:

globe.camera.position = Position.create();

This is supossed to be equivalent to this expression:

globe.getCamera().setPosition(Position.create());

I have no problem in creating the “first level” of getters/setters, the .camera part, like this:

function Camera() {

    var x,y,z;

this.__defineGetter__("camera", function() {
        alert("This is the camera getter");
});

    this.__defineSetter__("camera", function(position) {            
        alert("This is the camera setter");
});

}

...

globe=new Camera();
globe.camera=...
c=globe.camera;

...

But im not quite sure on how to define the position getter inside camera. I am trying something like this but it wont work:

function Position() {

    this.__defineGetter__("position", function() {
        alert("This is the position getter");
});

}

globe.camera=new Position();
pos=globe.camera.position;

The alert inside the getter wont show up. Any clue on this? Is it even possible to achieve this behaviour? I have searched quite a lot on Google but havent been able to hit the right search terms, and the examples for getters/setters tend to be very simple. Thanks in advance.

Answer 1

__defineGetter__ and friends are non standard.

var Camera = Object.create({}, {
  position: {
    get: function () {
      return Position.create();
    },
    set: function (p) {
      this._position = p;
    }
  }
});

Object.defineProperty(globe, "camera", {
  get: function () {
    return Object.create(Camera);
  }
});

Your going to want to use Object.defineProperty

However, why are you using getters and setters? They are evil. You should avoid them really unless your doing something clever.