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RE: Nested <bind>s

From: Alessandro Triglia <sandro@mclink.it>
Date: Thu, 27 Jul 2006 14:00:18 -0400
To: "'Erik Bruchez'" <ebruchez@orbeon.com>, <www-forms@w3.org>
Message-ID: <000301c6b1a6$8ac101b0$8b01a8c0@aldebaran>

Hi Erik,

See below.

 

> -----Original Message-----
> From: www-forms-request@w3.org 
> [mailto:www-forms-request@w3.org] On Behalf Of Erik Bruchez
> Sent: Monday, July 24, 2006 10:03
> To: www-forms@w3.org
> Subject: Re: Nested <bind>s
> 
> 
> Aaron Reed wrote:
> > 
> > Alessandro Triglia wrote:
> >> Hi
> >>
> >> I have another question.  What is the purpose and significance of 
> >> <bind> elements nested within another <bind> element?
> >>
> >> The schema allows nested <bind>s.  However, the normative 
> text does 
> >> not specify what they mean, and there are no examples showing such 
> >> nested <bind>s.
> >>
> >> Alessandro Triglia
> >>
> > 
> > Nested binds have been a point of debate for a while.  You 
> can probably 
> > find some of the debate on this very list.  I think that 
> the official 
> > stance for XForms 1.0 is that it isn't necessary to support 
> this to be 
> > 1.0 compliant since it hasn't been fully hashed out, yet.  
> I believe 
> > that some processors do support nested binds by allowing an 
> inner bind 
> > to be relevant to the bind element that contains it.
> > 
> > I thought that this was going to be addressed in 1.1, but I 
> don't see it 
> > there, yet.  Maybe someone from the WG can clarify the 
> status of this 
> > issue.  But in short, don't count on any form that you author with 
> > nested binds to work across the 1.0 processors.
> 
> Mmmh, that's probably one of those things in XForms 1.0 that 
> only appear 
> in the schema, I guess (like the nesting of xforms:output within 
> xforms:label, and interleaving of xforms:choices, xforms:item, and 
> xforms:itemset).
> 
> Yet the schema is normative, which means that supporting 
> nested binds is 
> actually required by 1.0 implementations.
> 
> I was not aware there was a real debate. The only possible 
> issue I think 
> was related to what an implementation should do when the parent bind 
> returns a nodeset with more than one element, and I think 
> (but somebody 
> please correct me if I am wrong) that this translates, like 
> in the case 
> of xforms:repeat and xforms:itemset, into applying the children bind 
> elements for each node of the outer bind. At least, that's 
> how this is 
> implemented in Orbeon PresentationServer, and it seems to 
> make perfect 
> sense.


Do you mean that, once the parent <bind> has selected a nodeset (to which one or more model item properties are to be applied), a child <bind> will use each node of that nodeset as the context node for its own relative location path, in order to apply additional model item properties to some descendent nodes?   I agree this can be useful.  Still, I believe that 3.3.4 should specify this usage, otherwise it would be up to the implementations to interpret the schema in this way or in any other way that looks reasonable.

I have another question.  Even though the Recommendation states (in clause 3) that "XForms always requires a host language", I would be very interested in seeing an example of an implementation that uses a mimimalistic host language (or none at all).  I can see potential applications of XForms where a form is rendered in some default way, without the assistance of a host language.  Any ideas or pointers?

Thanks!

Alessandro
Received on Thursday, 27 July 2006 18:01:56 GMT

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