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Re: Factual error was Re: Brainstorming: Best of all Worlds

From: Dave Raggett <dsr@w3.org>
Date: Fri, 23 Mar 2007 11:26:27 +0000 (GMT)
To: Ian Hickson <ian@hixie.ch>
cc: Sebastian Schnitzenbaumer <sebastian@dreamlab.net>, public-html@w3.org
Message-ID: <Pine.LNX.4.64.0703231125300.14145@localhost>

Hi Ian,

Thanks for your feedback - I am asking for some help from the forms 
working group and will get back to you soon with some answers.

  Dave Raggett <dsr@w3.org> http://www.w3.org/People/Raggett

On Thu, 22 Mar 2007, Ian Hickson wrote:

> On Thu, 22 Mar 2007, Dave Raggett wrote:
>> On Thu, 22 Mar 2007, Ian Hickson wrote:
>>
>>> Some people have suggested some features, like declarative
>>> calculations, but it isn't clear how those features would work (the
>>> XForms Transitional draft, as previously discussed, doesn't actually
>>> define how they would work for all cases -- according to the current
>>> definition, in fact, one would have to solve the halting problem to
>>> implement the spec). In the case of declarative calculations it is
>>> also not clear how the feature could be made to degrade gracefully
>>> without breaking full implementations.
>>
>> You are incorrect on this point. Please re-read the XForms Transitional
>> draft spec as I have clarified the wording based upon how my
>> implementation works, and it should be noted that this has been tested
>> on a much wider range of browsers than Web Forms 2.0 has at this point
>> in time.
>
> The new spec doesn't change the UA requirements, so you still (as far
> as I can tell) require UAs to do static analysis of turing complete code,
> which, here, reduces to the halting problem. (All you've done is made such
> cases non-conforming, but that doesn't affect the UA at all.)
>
> There are other problems, too, such as how to handle fields whose exact
> lists of dependencies themselves depend on other field, e.g. because
> the calculate="" field does something like:
>
>   calculate="document.forms[0][document.forms[0].field.value] + 1"
>
> It's also unclear to me how UAs should handle cyclic graphs (which can't
> be sorted topologically) or graphs whose dependencies are either truly or
> apparently random (e.g. because the field used depends on the return value
> of an XMLHttpRequest call to a remote server).
>
> -- 
> Ian Hickson               U+1047E                )\._.,--....,'``.    fL
> http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
> Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
>
>
Received on Friday, 23 March 2007 11:26:47 GMT

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