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RE: [F&O] Casting to xs:NOTATION, xs:QName not clarified

From: Frank Legler <legler@sigma.informatik.hu-berlin.de>
Date: Mon, 17 Jan 2005 17:58:44 -0800
To: "Michael Rys" <mrys@microsoft.com>
CC: <legler@informatik.hu-berlin.de>, "Laurens Holst" <lholst@students.cs.uu.nl>, <legler@informatik.hu-berlin.de>, <public-qt-comments@w3.org>
Message-ID: <jUsT.aNoTheR.mEsSaGe.iD.110601359614326@www.informatik.hu-berlin.de>

According to Ashok's mail from 5 Nov 2004
(http://lists.w3.org/Archives/Public/public-qt-comments/2004Nov/0019.
html)
is it "possible to construct xs:QName and xs:NOTATION from string 
literals"

If the casting table 
(http://w3.org/TR/xpath-functions/#casting-from-primitive-to-primitive)
applies for both casts and constructors, then there is a contradiction
in the F&O spec.

Regards,
Frank

Michael Rys wrote:
> The casting table applies to both forms:
> 
> So if the casting tables says that you cannot cast from one type to
> another, it applies to both cast as Type and Type().
> 
> Best regards
> Michael
> 
> 
>>-----Original Message-----
>>From: public-qt-comments-request@w3.org [mailto:public-qt-comments-
>>request@w3.org] On Behalf Of Frank Legler
>>Sent: Monday, January 17, 2005 10:24 AM
>>To: Laurens Holst
>>Cc: legler@informatik.hu-berlin.de; public-qt-comments@w3.org
>>Subject: Re: [F&O] Casting to xs:NOTATION, xs:QName not clarified
>>
>>
>>At Saturday, 15 January 2005, Laurens Holst <lholst@students.cs.uu.
>>nl> wrote:
>>
>>
>>>Frank Legler wrote:
>>>
>>>>Hello Ashok,
>>>>
>>>>Does that mean that it is possible to construct xs:QName and 
xs:NOTATION
>>>>from xs:string,
>>>>but it is not possible to cast xs:QName and xs:NOTATION from a xs:
>>>>string?
>>>
>>>From section 17.6 of XQuery 1.0 and XPath 2.0 Functions and Operators:

>>>
>>>"Casting from xs:string and xdt:untypedAtomic to xs:QName, xs:
NOTATION,
>>>or types derived from them is not possible because it requires 
knowledge
>>>of the namespace context. Constructor functions are available to
>>>construct values of these types provided that the lexical representation 

>>>is known statically."
>>>
>>
>>I still do not understand why we differentiate between casting and
>>construction here.
>>Given the following examples
>>  (1) "a" cast as xs:QName   (: invalid according to the spec :)
>>    and
>>  (2) xs:QName("a")          (: valid according to the spec :)
>>
>>Don't both examples require knowledge of the namespace context?
>>And why is a static evaluation possible for (2) but not for (1)?
>>
>>Regards,
>>Frank
>>





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Received on Tuesday, 18 January 2005 02:00:02 UTC

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