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RE: Use Case 5.32 Pipeline

From: <vojtech.toman@emc.com>
Date: Thu, 24 May 2012 02:53:23 -0400
To: <public-xml-processing-model-wg@w3.org>
Message-ID: <F3C7EBECE80AC346BE4D1C5A9BB4A41F2ED2B094D8@MX11A.corp.emc.com>
The idea clearly was that since the p:template *step* evaluates the XPath expressions in the template document, it uses the step XPath context, in which p:step-available() (and others) are not defined. But we don't say that explicitly.

We actually don't say that for p:filter, p:label-elements, p:split-sequence etc. either. But I think that sections 2.6.1 and 2.6.2 are clear enough:

"When a *step* evaluates an XPath expression [...], unless otherwise indicated by a particular step, it does so with the following initial context: ..."

Regards,
Vojtech

--
Vojtech Toman
Consultant Software Engineer
EMC | Information Intelligence Group
vojtech.toman@emc.com
http://developer.emc.com/xmltech


> -----Original Message-----
> From: innovimax@gmail.com [mailto:innovimax@gmail.com] On Behalf Of
> Innovimax W3C
> Sent: Thursday, May 24, 2012 1:06 AM
> To: XProc WG
> Subject: Re: Use Case 5.32 Pipeline
> 
> Interesting side effet
> 
> In the process of trying to propose some alternate rewriting using
> p:template
> 
> I did this
> 
> <p:declare-step xmlns:p="http://www.w3.org/ns/xproc"
>   xmlns:c="http://www.w3.org/ns/xproc-step" version="1.0">
>   <p:output port="result"/>
>   <p:template>
>     <p:input port="template">
>       <p:inline>
>         <root>
>           Is XQuery available { p:step-available('p:xquery') }
>         </root>
>       </p:inline>
>     </p:input>
>     <p:input port="source">
>       <p:empty/>
>     </p:input>
>     <p:input port="parameters">
>       <p:empty/>
>     </p:input>
>   </p:template>
> </p:declare-step>
> 
> And I get this error :
> 
> err:XD0023 : Invalid XPath expression: ' p:step-available('p:xquery')
> '. It is a dynamic error if an XPath expression is encountered which
> cannot be evaluated (because it is syntactically incorrect, contains
> references to unbound variables or unknown functions, or for any other
> reason).
> 
> My problem is that we didn't define in
> http://www.w3.org/TR/xproc-template/, what the XPath context contains
> !!
> 
> So I cannot even blame Calabash !!
> 
> Mohamed
> 
> 
> On Wed, May 23, 2012 at 8:45 PM, Alex Milowski <alex@milowski.com>
> wrote:
> > <?xml version="1.0" encoding="UTF-8"?>
> > <p:declare-step xmlns:p="http://www.w3.org/ns/xproc"
> >    xmlns:c="http://www.w3.org/ns/xproc-step" version="1.0">
> >    <p:output port="result"/>
> >    <p:choose>
> >        <p:when test="p:step-available('p:xquery')">
> >            <p:identity>
> >                <p:input port="source">
> >                    <p:inline><green/></p:inline>
> >                </p:input>
> >            </p:identity>
> >        </p:when>
> >        <p:otherwise>
> >            <p:identity>
> >                <p:input port="source">
> >                    <p:inline><red/></p:inline>
> >                </p:input>
> >            </p:identity>
> >        </p:otherwise>
> >    </p:choose>
> > </p:declare-step>
> 
> 
> 
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Received on Thursday, 24 May 2012 06:54:11 GMT

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