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Re: Help: use-when and p:episode

From: Norman Walsh <ndw@nwalsh.com>
Date: Tue, 10 Nov 2009 11:59:26 -0500
To: public-xml-processing-model-wg@w3.org
Message-ID: <m2iqdixqmp.fsf@nwalsh.com>
"Toman_Vojtech@emc.com" <Toman_Vojtech@emc.com> writes:

> I now actually think that in its present form, use-when is
> underspecified. A the moment, the spec says that use-when "must contain
> an XPath expression that can be evaluated statically". But what does
> that really mean? How does that affect XPath extension functions like
> p:step-available(), p:value-available() etc.?

It means that the expression cannot make any reference to the context
node, position, or size.

> For instance, does p:step-available() in use-when see only standard
> XProc steps, or also other nested or imported steps? What about cases
> like this:
> <p:declare-step type="ex:step1"
>                 use-when="p:step-available('ex:step2')">
>   ...
> </p:declare-step>
> <p:declare-step type="ex:step2"
>                 use-when="p:step-available('ex:step1')">
>   ...
> </p:declare-step>
> Personally, I think we will have to be more specific about what you can
> do in use-when, and what limitations are there if you use the XPath
> extension functions in use-when expressions.

Hmm. Yes. I'll have to think about that one.

                                        Be seeing you,

Norman Walsh <ndw@nwalsh.com> | Man is the only animal who causes pain
http://nwalsh.com/            | to others with no other object than
                              | wanting to do so.-- Schopenhauer

Received on Tuesday, 10 November 2009 17:00:07 UTC

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