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

From: Michael Rys <mrys@microsoft.com>
Date: Mon, 17 Jan 2005 16:25:01 -0800
Message-ID: <BAE415CEAA831548800F68C44E905AF501499E3D@RED-MSG-60.redmond.corp.microsoft.com>
To: <legler@sigma.informatik.hu-berlin.de>, "Laurens Holst" <lholst@students.cs.uu.nl>
Cc: <legler@informatik.hu-berlin.de>, <public-qt-comments@w3.org>

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 00:26:54 UTC

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