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Re: [Touch events] createTouchList should probably take a sequence, not an IDL array

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Wed, 28 Nov 2012 12:04:30 -0500
Message-ID: <50B6441E.2010507@mit.edu>
To: Arthur Barstow <art.barstow@nokia.com>
CC: public-webevents@w3.org
On 11/28/12 11:03 AM, Arthur Barstow wrote:
> v1 is a CR now and we will soon start the interop testing to exit CR and
> move to PR.

Yes.  I'm providing implementor feedback on the spec, like I'm supposed 
to in CR...

> It seems like the proposed API change would affect implementations

Actually, apart from black-box performance testing, it does not, 
precisely because the callee does not hold on to the list by reference. 
  It also doesn't affect them because there is nowhere to actually get a 
Touch[], so in practice callers will pass in a JS array, which will 
first get converted as if it were a sequence<Touch> anyway, then lead to 
creating an internal object to wrap the sequence, then will throw away 
that object at the end of the call.

Specifically, see http://dev.w3.org/2006/webapi/WebIDL/#es-array the "An 
ECMAScript value V is converted to an IDL array value of type T[] as 
follows:" bit and note that the first bullet point is always skipped in 
current implementations.

Received on Wednesday, 28 November 2012 17:05:04 UTC

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