[Harmony Proxies] Proposal: Property fixing

Mark S. Miller erights at google.com
Thu Jun 16 09:29:55 PDT 2011

On Thu, Jun 16, 2011 at 9:22 AM, Brendan Eich <brendan at mozilla.com> wrote:

> On Jun 16, 2011, at 9:18 AM, Mark S. Miller wrote:
> On Thu, Jun 16, 2011 at 9:15 AM, Brendan Eich <brendan at mozilla.com> wrote:
>> We should have no more attribute "keywords" in property descriptors than
>> we need to model the semantics we wish to reflect on via Object.* APIs and
>> intercede in via proxies. Do we really want to split "DontDelete" back out
>> of "configurable"?
> We do not. We need merely specify that (a non-frozen) array.length is
> configurable but that arrays refuse to delete them. This is just part of the
> magical length behavior provided by arrays, with the virtues that it can be
> faithfully emulated by proxies.
> Clever. To rephrase your previous reply to avoid double-negatives ("this is
> not guaranteed not to be magical"), "configurable properties may behave
> magically".

In retrospect, perhaps we should have named this attribute "magical" rather
that "configurable"? And it is shorter. (Just kidding ;).)

>  I agree it's the non-configurable magic that we should address.
> Bonus, I think this will simplify things in our implementation of Array
> length vs. the ES5 Object.* APIs.

Cool! Shrinking a case explosion is often a good sign.

> /be

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