Yes, I agree that separating them out is a good idea. Allen and I have been
working on this lately, and I've signed up to present private names at the
upcoming face-to-face. Our thinking has been along similar lines to what you
describe here.
Dave
On May 17, 2011, at 6:55 PM, Luke Hoban wrote:
> The Private Names strawman currently combines a new runtime capability (using
> both strings and private names as keys in objects) with several new syntactic
> constructs (private binding declarations, #.id). At the March meeting, I
> recall there was some support for the idea of separating these two aspects,
> and exposing the runtime capability also as a library that could be used in
> ‘text/javascript’.
>
> I added a comment to the Private Names strawman page to suggest how this
> could be done. The runtime behavior of the proposal is the same, but in
> addition, a library function “Object.createPrivteName(name)” is added which
> provides direct access to the internal CreatePrivateName abstract operation.
> This allows the use of private names in a more verbose form, but without
> needing new syntax – similar in spirit to the ES5 Object.* operations.
> Borrowing an example from the current proposal to illustrate:
>
> Using ‘text/harmony’ syntax:
> function Point(x,y) {
> private x, y;
> this.x = x;
> this.y = y;
> //... methods that use private x and y properties
> }
> var pt = new Point(1,2);
>
> Using ‘text/javascript’ syntax:
> function Point(x,y) {
> var _x = Object.createPrivateName("x");
> var _y = Object.createPrivateName("y");
> this[_x] = x;
> this[_y] = y;
> //... methods that use private _x and _y properties
> }
> var pt = new Point(1,2);
>
> There seem to be several benefits to this:
> (1) The private name capability can be made available to ‘text/javascript’
> (2) The feature is easily feature-detectable, with a fallback of using
> ‘_’-prefixed or similar pseudo-private conventions
> (3) The core functionality can potentially be agreed upon and implemented in
> engines earlier than full new syntax
>
> Luke
>
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