Action proxies

Mark S. Miller erights at
Sun Feb 3 08:04:14 PST 2013

On Sun, Feb 3, 2013 at 7:22 AM, David Bruant <bruant.d at> wrote:

> [...]
> This does indeed get rid of invariant checks while guaranteeing the
> invariants anyway and apparently not losing expressiveness. Wow.


> Was this discussed during the January TC39 meeting? Do notification
> proxies have a chance to replace direct proxies or is it too late?
> In the case it would be too late, could "throw ForwardToTarget" be
> considered?

I mentioned at the January meeting that we'll be experimenting with these
new notification proxies, to see if they cover all the motivating use cases
adequately. I'm increasingly hopeful, but have nothing to report yet. If
they do, then at the March meeting I will propose that we do not include
direct proxies in ES6. Since it is too late to introduce as radical a
change as notification proxies into ES6, I would propose that proxies as a
whole get postponed till ES7.

We'll all be sad to see proxies wait. But given how much better
notification proxies seem to be, if they work out, it would be a terrible
shame to standardize the wrong proxies in ES6 just because they're ready
and sorely needed. Of course, as with Object.observe, implementors are free
to ship things ahead of formal standardization. And notification proxies
are vastly simpler to implement correctly than direct proxies.

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