Re: layering is consistent and coherent

At 12:38 PM 2000-06-03 -0400, Clark C. Evans wrote:
>On Sat, 3 Jun 2000, Al Gilman wrote:
>> Namespaces, per se, don't posess identity.  
>
>As I remember, "identity" is the only operation
>which the specifification attempts to define.
>
>> There is no sufficiently useful and general equivalence 
>> test for namespaces by which to define namespace identity.
>
>No doubt, that some think this is the reason why we are here.
>
>> Identity for individual namespaces will be found in subclasses 
>> of namespaces, not in the namespace domain itself. 
>
>Ouch!
>
>> The XSLT namespace is an example of this.
>
>Yes, it defines namespace comparison requiring absolutization
>first.  

[You didn't retrieve the namespace I was referring to.]  If one follows the
URI-reference <http://www.w3.org/TR/xslt#xslt-namespace> and reads
paragraph 2.1 of the XSLT specification, one finds the language

   XSLT processors must use the XML namespaces mechanism [128][XML Names]
   to recognize elements and attributes from this namespace. Elements
   from the XSLT namespace are recognized only in the stylesheet not in
   the source document. The complete list of XSLT-defined elements is
   specified in [129][B Element Syntax Summary]. Vendors must not extend
   the XSLT namespace with additional elements or attributes. [...]

Clearly the authors of this specification thought that they were defining a
namespace, and that this namespace was to be used only under the further
restrictions that they stated in this document.  [They happen to have given
a fully-qualified absoluteURI as the text to be used as ns-attr in
instances conforming to this spec.]

This is a namespace.  It is not best identified as "the XSLT namespace,"
but rather as "the namespace used in the XSLT language."  Naming markup
element types and attributes with this namespace commits you to be
employing not just the namespace, but the XSLT _language_.  This is the
reality of namespaces today.  They don't come free of connotations.  The
idea that they do is an artifice of the Recommendation, not a general truth
about namespaces [in any practical definition of "per se."] or the body of
extant usage.

Al

Received on Saturday, 3 June 2000 15:55:35 UTC