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RE: [DM] Typed value for elements

From: Michael Rys <mrys@microsoft.com>
Date: Thu, 12 Feb 2004 01:43:08 -0800
Message-ID: <EB0A327048144442AFB15FCE18DC96C70205370F@RED-MSG-31.redmond.corp.microsoft.com>
To: "Jonathan Robie" <jonathan.robie@datadirect.com>, "XML Query Comments" <public-qt-comments@w3.org>

See below.

Best regards
Michael

> -----Original Message-----
> From: public-qt-comments-request@w3.org [mailto:public-qt-comments-
> request@w3.org] On Behalf Of Jonathan Robie
> Sent: Wednesday, February 11, 2004 6:03 PM
> To: XML Query Comments
> Subject: [DM] Typed value for elements
> 
> 
> The rules for dm:typed-value() are confusing and inconsistent for
> elements and document nodes. Here is an example that illustrates one
> set of problems: what is the result of the following query?
> 
>   <Cities>
>     <City>
>         <CityId>01</CityId>
>         <Longitude>100</Longitude>
>         <Latitude>32</Latitude>
>     </City>
>     <City>
>         <CityId>02</CityId>
>         <Longitude>54</Longitude>
>         <Latitude>24</Latitude>
>     </City>
>   </Cities> * 2
> 
> In the current specification, this question can not be answered unless
> we know the schema information associated with the Cities
> element.

[Michael Rys] 
Note that this example is a pretty meaningless expression. I do not
think that we should design for such meaningless cases.

> Here is the current set of rules:
> 
> 1. If the element has a known complex type, and it does not allow
> mixed content, then it raises a type error.
> 
> 2. If this element's type is xdt:untypedAny, the typed value of the
> element is its string value, as an instance of xdt:untypedAtomic, so
> this query evaluates to (2 * 0110032025424). This is surprising, and
> it is not useful for users.

[Michael Rys] This is not a problem of the rule but a problem of your
example. This rule makes lots of sense if you add leave numbers, or if
you apply a string function to an untyped complex element that contains
document markup.

> 3. If this element's type is known, and it allows mixed content, the
> typed value of the element is its string value, as an instance of
> xdt:untypedAtomic, so this query evaluates to (2 * 0110032025424).

[Michael Rys] This is only true if you are doing dynamic typing. And in
that case again, you have just shown that your query above is a bad
example.

 
> It would be much simpler and cleaner to say that dm:typed-value()
> returns an error for any node with child elements. This is
> incompatible with the behavior of XPath 1.0, but so is the current
> behavior for elements of known complex type.

[Michael Rys] This is a bad rule since it disregards the
document-centric use case where you want to apply string functions to
complex content.
 
> Jonathan
Received on Thursday, 12 February 2004 04:43:13 UTC

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