[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: XPath 1.5? (was RE: typing and markup)
> Here's one such issue: I want to write a query or a transform whose output > is guaranteed to be XHTML. I don't want to validate my output each time to > see if it succeeded. I have yet to see this done for any seriously complicated transform. If the transformation is sufficiently simple then you could do this without the type system, but are you really expecting to be able to typecheck a function mapping (say) docbook to XHTML and guarantee that given a valid docbook instance a valid XHTML instance will come out? This may be just about possible with the XQuery style, but is highly dubious with the recursive template style in XSLT. You really don't have a good enough handle on when the templates will fire in order to typecheck the whole transform (as opposed to individual component functions). This is just part of the general problem, Xquery appears to have loaded a lot of baggage on XSLT/Xpath for which the famous "use cases" are hard to find... > Nothing in our spec requires you to do this. [define schema types] No of course, but my point is that while I can see a lot of use using dtd/schema to constrain authoring, and can see use of schema simple types to allow provision of type aware functions for sorting and arithmetic, I can see no use for schema complex types at transformation-time. The fact that I don't _need_ to use them is hardly justification for them being there. Your guarantee of producing valid output _would_ be a justification but as I say, I don't believe that holds in XSLT (and remain to be convinced it holds for serious sized Xquery either). > I would find it very useful to know if a transform will always produce an > instance that will validate against some schema. Thats why we support > complex types. This story is currently more compelling for XQuery than for > XSLT, though, because the types for queries have been worked out in more > detail. I'd say it is plausible in Xquery and totally uncompelling in XSLT. But even if we accept your wording, where is the "use case" for foisting all this stuff onto Xpath and so XSLT? > Indeed. Yo! we agree on something:-) > This question has not been answered, it is an open issue. My own view is > that if the validation fails, XPath 2.0 and XQuery 1.0 should have > undefined behavior. So as one of the authors of Xpath 2 you are happy to casually break one of the most innovative and successful uses of Xpath 1? Interesting. David _____________________________________________________________________ This message has been checked for all known viruses by Star Internet delivered through the MessageLabs Virus Scanning Service. For further information visit http://www.star.net.uk/stats.asp or alternatively call Star Internet for details on the Virus Scanning Service.
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