W3C home > Mailing lists > Public > public-xml-processing-model-wg@w3.org > September 2007

Re: Namespace Fixup Proposal

From: Henry S. Thompson <ht@inf.ed.ac.uk>
Date: Thu, 06 Sep 2007 12:54:50 +0100
To: Norman Walsh <ndw@nwalsh.com>
Cc: public-xml-processing-model-wg@w3.org
Message-ID: <f5bd4wwhuut.fsf@hildegard.inf.ed.ac.uk>

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Norman Walsh writes:

> / Alex Milowski <alex@milowski.org> was heard to say:
> | There are some steps, like p:insert and p:replace, where fixup isn't
> | the correct thing.  Those steps should preserve the in-scope namespaces
> | so that any content that relies up it still works.
>
> How can fixup be the wrong thing? In fact, how does fixup even arise
> in p:insert or p:replace; they exchange elements and, assuming that
> the input document has the right namespace bindings, the output must,
> mustn't it?

Yes, but it still won't necessarily serialise without work, and it's
possible that serialising will introduce failure to round-trip.
Suppose the matrix has an ns-attribute for the default namespace, but
the included bit consists entirely of no-namespace elts.  The
serialised result will be borked.  To detect this, you have to look at
every node in the inserted tree.

> Allowing un-fixed-up markup to flow between steps lets it get deeply
> burried in documents through operations that wouldn't normally cause
> fixup to be necessary.

I don't understand.

> On a separate, but related, topic, I'm confused about how the SAX
> argument plays out. Why is it hard to do this fixup with SAX? When do
> you ever have to buffer more than one start element event?

SAX filters just pass along what you give them.  If we require NS fixup
between steps, everyone using a SAX substrate will have to put an NS
fixup filter _every_ pair of steps, won't they?

ht
- -- 
 Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                     Half-time member of W3C Team
    2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
            Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
                   URL: http://www.ltg.ed.ac.uk/~ht/
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Received on Thursday, 6 September 2007 11:55:18 GMT

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