On Jan 15, 2009, at 9:50 AM, Erik Arvidsson wrote:
Sorry for being late to the party.
Is there a reason why we need to restrict the argArray to apply this
much? I think it would be very useful to allow anything array like
here.
Please define "array like" and give examples (possibly including DOM
nodelists, which thanks to "live update" are are neither lists nor
arrays, rather more like cursors).
We had a structural type for it in ES4. ES3.1 has no such type system
or spec language. It's too late to add anything like this. But for
Harmony, proposing (possibly more than one) "array-like" notion that
could be used to extend the language is fair game.
/be
--
erik
2009/1/15 Brendan Eich <[email protected]>:
On Jan 14, 2009, at 9:16 PM, Mark S. Miller wrote:
On Wed, Jan 14, 2009 at 7:08 PM, Brendan Eich <[email protected]>
wrote:
When in doubt, use brute force. ES3 already did. Quoting from its
spec for Function.prototype.apply:
15.3.4.3 Function.prototype.apply (thisArg, argArray)
[...] Otherwise, if argArray is neither an array nor an arguments
object (see section 10.1.8), a TypeError exception is thrown. If
argArray is either an array or an arguments object, the function
is passed the (ToUint32(argArray.length)) arguments argArray[0],
argArray[1], …, argArray[ToUint32(argArray.length)–1]. [...]
Yes, this is the spec text I quoted as well. But I don't understand
it or your "use brute force" answer.
Sorry, didn't mean to rehash.
How does Function.prototype.apply determine that argArray is an
arguments object?
ES1-3 leave this unspecified. But they talk about "an arguments
object [being] created" (10.1.8), etc. and it's easy enough to
implement the spec -- there are many implementations. SpiderMonkey
uses a distinct class whose name is "Object", to satisfy what is
specified ([[Prototype]] is the original Object.prototype value).
Do we need really need to say more?
We need to do something, since as it stands the operational spec is
unimplementable in terms of the specified semantic state.
The spec has a domain of discourse that includes "an arguments
object". It's implementable without error. Sure, we could add
another internal property to avoid this appeal to an unspecified
way of distinguish arguments objects from all other objects. Again
I'm loath to over-invest.
/be
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