es-discuss Digest, Vol 46, Issue 22

thaddee yann tyl thaddee.tyl at
Thu Dec 23 08:36:45 PST 2010

The private names proposal has a lot of good ideas, but their use is
not obvious.
The reasons I see for that are:
The "private a;" declaration:
* changes meaning of all obj.a in scope
* looks like a scoped variable, not a private element of an object
* is not generative-looking
... which makes it harder to understand, and use.

I find that David Herman's proposal fixes those issues:
>But your idea suggests yet another alternative worth adding to our growing pantheon. We could allow for the scoping of private names, but always require them to be prefixed by the sigil. This way there's no possibility of mixing up public and private names. So to use an earlier example from this thread (originally suggested to me by Allen):
>   function Point(x, y) {
>       private #x, #y;
>       this.#x = x;
>       this.#y = y;
>   }

I understand that the number sign gets really heavy and annoying after
some time. As a result, I suggest a simpler syntax, "private

a = {};
k = {a: a};
a['k'] = k;
function aa(o) {
  private .a;
  k..a = o;  // or: private c.a; c.a = o;
  a.a = a.k.a;  // or: a['a'] = a['k']['a'];
  a.a = k..a;  // here, on the other hand, k.a is the private stuff.
  return .a;
let a2 = aa(a);
print( a[a2] === a );  // true

Would this syntax be less Perlish?

ps: my understanding is that, using the current specification,
print(a[a2] === a.k.a) from my earlier email yields true, not false,
since (a.k.a === a). Am I wrong?

On Wed, Dec 22, 2010 at 12:40 AM, Brendan Eich <brendan at> wrote:
> a = {};
> k = {a: a};
> a['k'] = k;
> function aa(o) {
>  private a;
>  k.a = o;
>  a.a = a.k.a;
>  return #.a;
> }
> print(a[a2] === a.k.a);
> false
> Note that (a[a2] === a.k[a2] && a[a2] === a).
> This is all kind of plug-and-chug from my reading of the strawman. Was it
> unclear in a way where you could suggest a fix? Or maybe it just didn't
> start with a minimal statement of the rules.
> /be

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