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Re: Would it make sense for Web IDL [[Call]] to do the current execution context munging that ES6 functions' default [[Call]] does?

From: Allen Wirfs-Brock <allen@wirfs-brock.com>
Date: Thu, 28 Aug 2014 11:22:15 -0700
Cc: "public-script-coord@w3.org" <public-script-coord@w3.org>
Message-Id: <6AA671F8-62C3-4C3D-AA0E-46CA2BCF01C5@wirfs-brock.com>
To: Boris Zbarsky <bzbarsky@mit.edu>

On Aug 28, 2014, at 11:03 AM, Boris Zbarsky wrote:

> On 8/28/14, 1:37 PM, Allen Wirfs-Brock wrote:
> 
>> Not sure what you mean by "If WebIDL function munged the current
>> execution context".
> 
> What I had meant was performing the steps at http://people.mozilla.org/~jorendorff/es6-draft.html#sec-built-in-function-objects-call-thisargument-argumentslist (thank you for the link; I was looking at http://people.mozilla.org/~jorendorff/es6-draft.html#sec-ecmascript-function-objects-call-thisargument-argumentslist before that, which has a bunch of complications that don't seem relevant here).
> 
>> From an ES perspective I expect that every [[Call]] to a WebIDL
>> function suspends the calling execution context and establishes a new
>> execution context in conformance to [3].
> 
> Ah, I see.  I had recalled Web IDL defining its own [[Call]] for methods, but looks like it does not.  It just talks about "a Function object whose behavior is as follows".  So it should just explicitly say this is a "built-in Function object" and then I think we're good, mostly, right?

Yes, the extension points I intended are in steps 7 and 9 of 9.3.1. But remember that a "built-in function" is allowed to be implemented as an ECMAScript function in which case any additional special WebIDL processing would have to be done in the body of the function.

> 
> I say mostly, because there _are_ some cases where Web IDL defines its own [[Call]].  Specifically, for constructors and legacycallers.  Is there a way those [[Call]] definitions could just have the steps of #sec-built-in-function-objects-call-thisargument-argumentslist performed without copy/pasting them?

That's fine.  You should be able to do whatever you need as part of the step 7 or 9 extension points. Or, you can define a new [[Call]] that is a superset of that specified in 9.3.1.

allen
Received on Thursday, 28 August 2014 18:22:47 UTC

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