If you are not paranoid, you can just use nonwritable properties. That forces
you to use `Object.defineProperty` to change the value, so you are protected
against accidental assignments.
function Obj() {
Object.defineProperty(this, 'x', { value: 2, writable: false,
enumerable: true, configurable: true })
this.setX = function (val) {
Object.defineProperty(this, 'x', { value: val })
}
}
o = new Obj
o.x = 17 // assignment will fail; moreover, in strict mode, an error is
thrown
o.x // 2
o.setX(18)
o.x // 18
It doesn't prevent the user from hanging themself with
`Object.defineProperty(o, 'x', { value: 17 })`; but at least, it won't be by
chance!
—Claude
Le 13 déc. 2013 à 14:34, raul mihaila <[email protected]> a écrit :
> Hello, was there any proposal for object properties that can be read from
> anywhere but are writable only from the execution context where the name
> associated with the property was defined? Something like:
>
> function Obj() {
> ro x; // read only name x
> this.x = 2;
> this.setX = function (val) {
> this.x = val;
> };
> }
>
> var o = new Obj;
>
> o.x; // 2
> o.x = 43; // throws some error
> o.x; // 2
> o.setX(100);
> o.x; // 100
>
> The advantages would be that you are sure that there are no side effects when
> the property is accessed and also I'm guessing you have no function call
> overhead.
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