Namespaces hate validation!

[John Cowan]

Murray Altheim wrote:

> Only on document instances that are already valid.

If the instance is well-formed and namespace-compliant, then Tim's
algorithm will work whether the instance is valid or not.

> You complain about
> Murray's faulty logic, but this whole concept of 'preprocessing' an
> instance is so unclean as to be unusable. The whole reason for doing
> validation is to determine that it's safe to perform processing.

Safe to perform processing of certain kinds.  Some processing requires
only WFness, some requires validation, some requires validation and
then further correctness checking.  In this case, it is safe to
change the prefixes on documents and move namespace-declaring attributes
to the root element as long as the document is WF and namespace-correct.
Indeed, the resulting instance is namespace-equivalent, in the sense
that a namespace-aware processor that doesn't look at namespace
declarations directly will not know the difference.

> You
> can't begin processing before you perform processing unless you've
> already done some processing to determine that the processing you're
> planning to do is going to be safe processing.

True.

> In other words, you can't
> work on the derived product of an invalid instance.

False.

The instance can be invalid and still be processable by
processes that expect only WFness, as is the case here.

-- 
John Cowan	http://www.ccil.org/~cowan		cowan at ccil.org
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)

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