Action proxies

Brendan Eich brendan at
Mon Feb 4 14:11:42 PST 2013

Mark S. Miller wrote:
> On Mon, Feb 4, 2013 at 1:36 PM, Brendan Eich <brendan at 
> <mailto:brendan at>> wrote:
>     Tom Van Cutsem wrote:
>         2013/2/4 Brendan Eich <brendan at
>         <mailto:brendan at> <mailto:brendan at
>         <mailto:brendan at>>>
>             If notification proxies require allocation per trap
>         activation,
>             that's a fatal flaw in my view.
>         Did you mean to say action proxies? Action proxies do require
>         allocation per trap activation, and I also considered this a
>         fatal flaw.
>     I was replying to Mark, so meant notification proxies.
>         Notification proxies require allocation of a post-trap when
>         they need to do something after the operation was performed on
>         the target.
>     Yes, and (just to respond to Mark's somewhat premature "maybe
>     notification proxies will defer proxies from ES6") that seems like
>     a fatal flaw, in spite of the post-trap condition.
> Saying that a maybe is premature seems a bit much.

I think you're getting ahead of consensus in a "what if?" way, which is 
fine (like the Marvel Comics "What If? Dr. Doom became Spider-Man!" ;-).

But fair's fair, so I thought it worth giving some countervailing 
contingent feedback.

> In any case, you may be right that this is a fatal flaw. You're making 
> a performance-based argument, and it is certainly premature one way or 
> the other to predict how these relative costs will balance out. Let's 
> wait till we have more data.

We are not going to defer proxies from ES6 in order to implement 
notification proxies and find they cost too much. We know enough about 
allocation dwarfing other costs (direct + GC indirect), I bet. Happy to 
find out more from experiments but since we are just saying "what if?" I 
will talk back -- and make a wager on the side if you like.

IOW, I argue that while it's ok to speculate, doing so in one direction 
(in favor of notification proxies) does not mean data must gathered to 
prove a cost is "too much" in order to not defer proxies from ES6. For 
some applications, any cost is too much, so no data is needed.


More information about the es-discuss mailing list