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Re: Deleting in a viewport

From: Alex Milowski <alex@milowski.org>
Date: Fri, 10 Nov 2006 08:07:57 -0800
Message-ID: <4554A3DD.6000701@milowski.org>
To: public-xml-processing-model-wg@w3.org

Jeni Tennison wrote:
> Hi,
> Alex Milowski wrote:
>> Norman Walsh wrote:
>>> / Alex Milowski <alex@milowski.org> was heard to say:
>>> | I'm not certain we have a good way to do this because a viewport
>>> | always requires an output for the replacement.
>>> |
>>> | Any ideas how we might solve this?
>>> With an p:empty component that takes no inputs and returns an empty
>>> document sequence?
>> I thought about that... but we don't say how empty sequences are
>> handled.
>> I suppose we could say that a viewport's replacement must either
>> be a singleton sequence or an empty sequence.  An empty sequence
>> has the effect of deleting the matching subtree.
> I was assuming that we'd allow an empty <p:output> if we wanted the 
> output to be bound to an empty sequence. Note that this is required 
> within <p:when>/<p:otherwise> as well, for situations where the 
> <p:choose> is effectively splitting a sequence of documents onto two 
> output ports.
>  <p:choose step="previous" source="result">
>    <p:when test="/foo">
>      <p:output port="foos" step="previous" source="result" />
>      <p:output port="bars" />
>    </p:when>
>    <p:otherwise>
>      <p:output port="foos" />
>      <p:output port="bars" step="previous" source="result" />
>    </p:otherwise>
>  </p:choose>
> I was also assuming that a viewport's replacement could be a sequence of 
> documents, in which case the original element is replaced by the 
> concatenation of that sequence. This makes it easy to use viewport to 
> insert elements into a document.
> I agree with Henry that we need a 'delete' built-in component as well.

This is all good and right in line with my thinking.  I had both a
delete component in smallx as well as the ability to replace an
element with a sequence of elements in a viewport.

I think we should add a delete and/or empty step.  I'll try to put
something into the standard component list.

--Alex Milowski
Received on Friday, 10 November 2006 16:08:08 UTC

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