RE: computed namespace constructors

The "computed namespace constructors" are not really constructors but
like the xmlns namespace attributes in the XML syntax a way to bind new
prefixes to namespace URIs. As such they indeed change the static
context.

You cannot use an expression in XQuery 1.0 to give a namespace URI...

Best regards
Michael

> -----Original Message-----
> From: public-qt-comments-request@w3.org [mailto:public-qt-comments-
> request@w3.org] On Behalf Of Per Bothner
> Sent: Monday, November 24, 2003 11:01 PM
> To: public-qt-comments@w3.org
> Subject: computed namespace constructors
> 
> 
> The semantics of computed namespace constructors is unclear:
> 
>    3.7.3.7 Computed Namespace Constructors
>    A constructed namespace node ... binds a namespace prefix
represented
>    as NCName in the syntax) to a URI and adds the namespace prefix to
the
>    in-scope namespaces for its enclosing element.
> 
> But the "in-scope namespaces" is part of the *static* context, and
> constains both prefix *and* URIs:
> 
>    [Definition: In-scope namespaces. This is a set of (prefix, URI)
>    pairs. The in-scope namespaces are used for resolving prefixes used
>    in QNames within the expression.]
> 
> So how can a run-time namespace expression add to the static in-space
> namespaces?
> 
> It might be possible to change the sementics so only the namespace
> prefixes is part of the static context, while the namespace uri is
> part of the dynamic context, but that would certainly complicate
> implementation and probably the semantics  Consider:
> 
> element {$ename} {
>     namespace xx { myns:f($myns:x) },
>     namespace myns
>        {if $version eq 1 then "http://example.org/v1"
>         else "http://example.org/v2"},
>     attribute xx:type {"myns:invoice"},
>     $content
> }
> 
> This has a forward reference to the myns namespace (is that allowed?),
> and an function name, a variable name, and an attribute name, all of
> whose namespaces have to be calculated at run-time.  I assume the
> intention is to not allow that.
> 
> I suggest a separate concept of "active namespaces" consisting of
> anmespaces declared in namespace attributes and namespace
constructors.
> This could be part of the dynamic environment, but not the static
> environment.
> --
> 	--Per Bothner
> per@bothner.com   http://per.bothner.com/
> 
> 
>