SAX2 Namespace Support

David Megginson david at
Wed Jan 5 23:58:34 GMT 2000

Leigh Dodds <ldodds at> writes:

> > In principle (the principle of least surprise), it's very bad
> > behaviour for two objects to be == in C++ or equals() in Java if any
> > of their publicly-accessible fields differ.  Think of sets, for
> > example.
> In this instance though your level of surprise is going to relate 
> to how familiar you are with the Namespaces spec.

Expect close to zero, here -- judging by the e-mail I receive, most
people who use SAX haven't even read the XML 1.0 REC much less the
Namespaces REC, and I wouldn't expect them to have done so.  After
all, they're programmers who have to deal with XML as one (often
small) part of their work, not XML specialists.  

I should note that I've never read the Java Language Specification or
the the Unicode spec (either of them) cover-to-cover, though I work
with Java and Unicode almost daily.


> The problem though boils down to how often, in reality, XML instances 
> will have the same Namespace declared twice, with different prefixes.

The fact that the bug would be rare makes it worse -- an application
will run perfectly for, say, 18 months, then will suddenly and
inexplicably blow up long after the original programmers have moved on
because one input document happened to declare the same NS twice and
the programmers didn't build in error recovery for that problem.

All the best,


David Megginson                 david at

xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev at
Archived as: and on CD-ROM/ISBN 981-02-3594-1
To unsubscribe, mailto:majordomo at the following message;
unsubscribe xml-dev
To subscribe to the digests, mailto:majordomo at the following message;
subscribe xml-dev-digest
List coordinator, Henry Rzepa (mailto:rzepa at

More information about the Xml-dev mailing list