ECMA TC 39 / W3C HTML and WebApps WG coordination

Brendan Eich brendan at mozilla.com
Fri Sep 25 12:35:38 PDT 2009


On Sep 25, 2009, at 12:08 PM, Jonas Sicking wrote:

> On Fri, Sep 25, 2009 at 9:56 AM, Brendan Eich <brendan at mozilla.com>  
> wrote:
>> My positions are:
>>
>> 1. WebIDL, the bird in the hand (I agree with Sam: go invent  
>> something
>> better, come back when you're done).
>>
>> 2. Don't keep perpetuating catchall patterns, they are confusing for
>> developers and costly for implementors and static analysis tools,  
>> even if
>> implementable in some future ES edition.
>>
>> 3. Don't care.
>
> Regarding 2. How do you feel about index accessors? I.e. for example  
> you can do:
>
> myNode.children[5]
>
> which returns the same as
>
> myNode.children.item(5)
>
> This seems equally impossible to implement in ECMAScript, but is
> something that I think is helpful to authors so not something that I
> want to stop adding to new interfaces.

Good point. I have mixed feelings, to be honest. See the ArrayLike  
thread on es-discuss:

https://mail.mozilla.org/pipermail/es-discuss/2009-May/009300.html

and followups. The one from Travis Leithead of Microsoft at:

https://mail.mozilla.org/pipermail/es-discuss/2009-May/009363.html

links to http://dev.w3.org/2006/webapi/WebIDL/#es-sequence, which has  
words about an "Array host object":

http://dev.w3.org/2006/webapi/WebIDL/#dfn-array-host-object

This is new and different from the legacy collection/nodelist stuff,  
which we can't change. Is it the new-model solution for index  
accessors, or are you still wanting to make live "tree cursors" with  
indexed getter and setter catchalls?

The live tree cursors always seemed like a mixed bag at best. Folks  
want to use Array generic methods on them, and sometimes find the  
liveness a problem. I've not heard anyone saying the liveness was a  
crucial win.

/be


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