On Wed, Jul 27, 2011 at 5:02 PM, David Herman <dher...@mozilla.com> wrote:
> > I've been exploring private name objects [1] and I'm a bit confused by a > few things in the proposal, especially the Reflection example... > > The page was out of date, sorry. I've updated the page to reflect the > agreement we came to in the last face-to-face, which was that private names > should not be reflected anywhere except to proxy traps. This leaks less > information than what was on the wiki. In particular, now you can't figure > out how many private names an object is carrying around. > Perfect! This is exactly what I was hoping for. [snip] I've separated this out on the wiki page as a remaining open issue. I'm not > sure if we've come to consensus about this case. (One concern was that > Object.getOwnPropertyNames() and for...in no longer are guaranteed to > produce strings, although this is mitigated by the toString() coercion of > the name objects.) > > > I also see no mention of what `str` should default to in Name.create, > even though it's defined as optional and is quite significant as the > name.public.toString return value. Is there something like a unique string > value planned for this? At the very least the proposal should hint at what > Name.create().public.toString() should return (assuming it's not undefined). > > This hasn't been settled yet. IMO, I don't think it needs to be guaranteed > to be unique. The uniqueness guarantee is about the *identity* of the > object, and strings are forgeable, even if they're unique at the time they > are created. > Understood WRT the forgeability of strings -- I was more concerned with the potential hazard of toStringing the values of an own-names array, only to find out you have several keys with the string value "undefined". Sure you're doing it wrong, but string keys are an es5 invariant -- it's bound to happen, as you hinted at in your reply. But now that you've clarified the reflection semantics it's clear that this is not much of an non-issue for non-reflective "private" names, just another note for proxy authors. Of course, if the visibility flag becomes harmonious (and I really hope it does!) it's still a bit of a problem for these "unique" names. There's no need for unforgeability here so a unique string could be used, but it's probably too much magical and too little help -- if unintentionally used (the result of an own-names string coercion) it papers over a deeper semantic bug. Better would be to throw, but there's no sane way to do that. Ah well, this is great stuff. Thanks again, Dave... Dean
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