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Re: towards consensus on fixup, part 2

From: Alex Milowski <alex@milowski.org>
Date: Fri, 7 Sep 2007 11:12:17 -0700
Message-ID: <28d56ece0709071112y15ab83e1h170f96f17c452633@mail.gmail.com>
To: public-xml-processing-model-wg@w3.org

On 9/7/07, Norman Walsh <ndw@nwalsh.com> wrote:
> / Alex Milowski <alex@milowski.org> was heard to say:
> | For example, p:insert or p:replace take whole element subtrees
> | and put the into another document.  If those elements have dependencies
> | on in-scope namespaces, you'd break the content if the in-scope namespaces
> | aren't copied.  If you rely upon namespace fixup, you'd only get
> | namespace declarations for the elements and attributes of that subtree and
> | not extra ones that exist for the content (as they weren't copied).
>
> Why? The node that you're inserting has some number of in-scope
> namespaces. I'd expect namespace fixup to preserve all of them without
> regard to which ones were (or weren't) actually needed on the element
> or its descendants.

An implementation of p:insert/p:replace that does not perform any
namespace fixup in the step could drop very easily omit all the in-scope
namespaces that come from ancestors of the inserted or replacement
element.  That is, they copy only the declarations that exist and
ignore the superset that is the in-scope namespaces.

I want to avoid this by being explicit in the description of the step and
say that in-scope namespace must be preserved.

>
> Perhaps we should tweak our definition of namespace fixup a little bit
> to make that clearer:
>
>   [Definition: Some steps can produce XML documents which could not
>   have been produced by directly parsing any instance document
>   (because they contain nodes which have in-scope namespaces that are
>   not declared or in-scope namespaces with conflicting prefixes, for
>   example). To represent such a document in a serializable way, the
>   XProc processor must sometimes add additional namespace nodes,
>   perhaps even renaming prefixes, to satisfy the constraints of
>   Namespaces in XML. This process is referred to as namespace fixup.]

I don't see how this solves the problem.

-- 
--Alex Milowski
"The excellence of grammar as a guide is proportional to the paucity of the
inflexions, i.e. to the degree of analysis effected by the language
considered."

Bertrand Russell in a footnote of Principles of Mathematics
Received on Friday, 7 September 2007 18:12:22 GMT

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