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Re: [WebIDL] Dictionaries and undefined

From: Cameron McCormack <cam@mcc.id.au>
Date: Mon, 19 Dec 2011 13:26:56 +1100
Message-ID: <4EEEA0F0.5010906@mcc.id.au>
To: Jonas Sicking <jonas@sicking.cc>
CC: Brendan Eich <brendan@mozilla.org>, Erik Arvidsson <arv@chromium.org>, "Mark S. Miller" <erights@google.com>, Dominic Cooney <dominicc@google.com>, public-script-coord@w3.org
On 31/10/11 9:22 AM, Cameron McCormack wrote:
> Yes, we did just resolve as part of the previous Last Call comment
> resolution lot that undefined is treated as a missing argument. Making
> dictionary members treat undefined as an explicit value would be
> inconsistent with that. I'd rather have both be the same, and given the
> reasonably extensive discussion that were already had with the function
> calling case, I'd lean on the side of making undefined the same as an
> unspecified dictionary member.

I was going to make this change, but I now feel a bit trepidatious about 
the issue this aligns with (explicit undefined passed to optional 
operation arguments meaning "argument omitted"), given Erik's and 
Brendan's comments above.  They were in contradiction with the belief we 
eventually settled on in the thread beginning at 
http://www.w3.org/mid/4E2580C8.6050106@lachy.id.au that comparing 
argument values to undefined rather than looking at arguments.length is 
more common.  I think it would be unfortunate if ES6 function argument 
default values behaved differently from APIs define with Web IDL.
Received on Monday, 19 December 2011 02:27:41 UTC

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