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Re: context for origin on xf:insert

From: David Landwehr <david.landwehr@picoforms.com>
Date: Fri, 10 Aug 2007 09:24:47 +0200
Message-Id: <6AC375E7-89C6-4B62-A267-CCDFC46A2306@picoforms.com>
Cc: www-forms@w3.org
To: Aaron Reed <aaronr@us.ibm.com>

It is always a head spinner dealing with the insert action and all  
these conditions depending on if an attribute is present or not.

My feeling is that a declarative language should be so simple that  
the author should immediately be aware what a specific action is  
doing without going into a big analysis. I think that the insert  
action does not provide the clarity and simplicity it ought to and  
that this can also be proven that implementors keep coming up with  
questions and problems regarding the action.

This problem could be solved by spitting the functionality of insert  
(and maybe delete) up in separate actions which will provide  
simplicity and clarity.

Best regards,
David



On Aug 10, 2007, at 1:41 AM, Aaron Reed wrote:

>
> Hi,
>
> In XForms 1.1, I have a question about @bind.  The contents of this  
> question are inspired by a testcase on a bug opened against our  
> Mozilla XForms extension (https://bugzilla.mozilla.org/show_bug.cgi? 
> id=391586).
>
> If I have:
>
>   <xf:group ref="instance('containers')/source/date">
>     <xf:trigger>
>       <xf:label>copy source date (containing text)</xf:label>
>       <xf:action ev:event="DOMActivate">
>         <xf:insert bind="date" origin="." position="after" at="1"/>
>       </xf:action>
>     </xf:trigger>
>   </xf:group>
>
> should the context node for the evaluation of @origin's XPath  
> expression be the result of the evaluation of @bind?  Or should the  
> context node for @origin be instance('containers')/source/date?
>
> The spec says -> "The insert context is determined. If the bind  
> attribute is present or if the context attribute is not given, the  
> insert context is the in-scope evaluation context. Otherwise, the  
> XPath expression provided by the context attribute is evaluated  
> using the in-scope evaluation context, and the first node rule is  
> applied to obtain the insert context." I would think that the  
> result of @bind's evaluation would be the context node since that  
> is how xpath evaluations are evaluated on almost every other xforms  
> element in the spec (for example setvalue) and this would also  
> logically explain why @context is ignored if @bind is present.  But  
> both the Orbeon and Sidewinder implementations seem to think that  
> the context should be instance('containers')/source/date.
>
> I assume one of us is right :)  And I am guessing that it is  
> probably Orbeon and Sidewinder since the spec mentions in-scope  
> evaluation context instead of 'Nodeset binding'.  However, it is  
> quite confusing to have 'Node Set Binding' attributes mentioned in  
> the insert action, have @context ignored if @bind is present, but  
> then not have @bind provide context for the xpath evaluations even  
> though it provides context elsewhere in the spec.  It might be  
> worth a special mention in the spec.
>
> Thanks for your help,
> --Aaron
>
>
>
Received on Friday, 10 August 2007 07:25:44 GMT

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