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Re: XForms 1.1 - target of the xforms-delete event

From: Erik Bruchez <ebruchez@orbeon.com>
Date: Tue, 2 Jun 2009 15:56:19 -0700
Cc: Forms WG <public-forms@w3.org>, xforms <www-forms@w3.org>, www-forms-editor@w3.org
Message-Id: <3917C40B-8141-4189-A821-368A0F505751@orbeon.com>
To: John Boyer <boyerj@ca.ibm.com>
John,

Got it.

This said, it would be disturbing to me that xforms:delete could  
actually support deleting nodes from multiple instances simply because  
XPath allows it, but that we would artificially prevent this from  
working.

Either way, you would have to modify the spec to reflect either 1) the  
NOP behavior or 2) the event dispatch.

Right now we say in "10.4 The delete Element":

   "The delete action is successfully completed by dispatching the  
xforms-delete event with appropriate context information."

It seems to me that it would be as easy to simply say:

   "The delete action is successfully completed by dispatching the  
xforms-delete event with appropriate context information to any  
instance from which nodes were deleted."

And from the implementor's perspective, it doesn't make a big  
difference either. The win is increased consistency.

-Erik

On Jun 2, 2009, at 11:31 AM, John Boyer wrote:

>
> Hi Erik,
>
> I think there's a misunderstanding.  I wasn't saying that the delete  
> *event* would not occur, but rather that the delete *action* itself  
> should no-op if you try to delete nodes from multiple instances.
>
> I quite agree that the delete event would be useless if you couldn't  
> count on it to let you know whenever nodes are deleted by an XForms  
> supported mechanism (unfortunately, you're on your own with the DOM  
> API).
>
> But I think form authors don't lose very much in practice if a  
> delete action just simply doesn't work if you do a multiple instance  
> delete.  If you want to delete from multiple instances, just write  
> multiple deletes.  Multiple instance deletes are uncommon, and there  
> is no effective change of the number of achievable applications by  
> this limitation since the number of instances is static.
>
> Also, my consistency argument is about the actions, not the events.   
> The XForms insert action can only insert into one instance, so it is  
> reasonable to have an XForms delete action that can only delete from  
> one instance.  The events are just there to target the instance that  
> was mutated by the action.
>
> This is the best limitation at this stage of XForms 1.1 since our  
> only test on the xforms-delete event tests a deletion from a single  
> instance.  There is no test coverage for multiple instance deletion,  
> so if we modify the spec to say it is possible, then we need a test  
> and two conforming implementations.  Given the above claim that  
> there is no loss of power and no significant inconvenience in  
> practice, it does not seem worth the trouble.
>
> Cheers,
> John M. Boyer, Ph.D.
> STSM, Interactive Documents and Web 2.0 Applications
> Chair, W3C Forms Working Group
> Workplace, Portal and Collaboration Software
> IBM Victoria Software Lab
> E-Mail: boyerj@ca.ibm.com
>
> Blog: http://www.ibm.com/developerworks/blogs/page/JohnBoyer
> Blog RSS feed: http://www.ibm.com/developerworks/blogs/rss/JohnBoyer?flavor=rssdw
>
>
>
>
> From:
> Erik Bruchez <ebruchez@orbeon.com>
> To:
> Forms WG <public-forms@w3.org>
> Cc:
> xforms <www-forms@w3.org>, www-forms-editor@w3.org
> Date:
> 05/27/2009 11:02 AM
> Subject:
> Re: XForms 1.1 - target of the xforms-delete event
>
>
>
>
> > Another possible fix is to have xforms delete ignore nodes which are
> > not in the same instances as the first node, or to no-op entirely.
>
> This would make the xforms-delete event much less useful.
>
> > Insert can only insert nodes into one instance, so it is reasonable
> > to have consistency with delete.   When delete was changed from one
> > node to many nodes, the most urgent requirement we had in mind to
> > satisfy was deletion of a set of children of a given node.  This can
> > reasonably expand to nodes having a common ancestor, but crossing
> > DOMs just seems a little much, esp. without the analogous insert
> > ability.
>
> I don't buy the consistency argument here.
>
> We have to look at events from the perspective of form authors, not
> XForms implementors.
>
> If xforms-delete is an event you can listen to to figure out that
> nodes were inserted into a given instance, then it needs to be
> dispatched to an instance when nodes are removed from it. If
> xforms:delete is able to delete events from more than one instance,
> then it follows that xforms-delete must be dispatched to all instances
> from which nodes were removed.
>
> If we can't rely on an event to be accurately dispatched, then we
> should think about removing that event altogether.
>
> -Erik
>
> --
> Orbeon Forms - Web Forms for the Enterprise Done the Right Way
> http://www.orbeon.com/
>
>
>
>

--
Orbeon Forms - Web Forms for the Enterprise Done the Right Way
http://www.orbeon.com/
Received on Tuesday, 2 June 2009 23:03:08 UTC

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