[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message]

Re: SAX2: Namespace Processing and NSUtils helper class

  • From: David Brownell <david-b@p...>
  • To: james anderson <James.Anderson@m...>
  • Date: Wed, 05 Jan 2000 11:45:13 -0800

james anderson null
james anderson wrote:
> 
> hmm..., the thread is becoming rather tenuous, but, if you concur, that
> {"","a",""}, which is descibes <... xmlns="" ... > is not the same as {
> undeclared, "a", valid-prefix }, then how does the notion of nonconformance
> enter into the question re
> 
> > > > {"", "a", ""} == {"", "a", "html"}
> 
> ?

Tim pointed out the spec only allows a null URI in the case of the
default namespace declaration:  xmlns="".  Prefix declarations may
not have a null URI:  xmlns:html="" is someone's bad.  Likewise is
a reference to an undeclared "html" prefix.

At the moment I won't suggest how to expose the former error, but
I'd thought it was pretty clear how to expose the latter.

- Dave


> David Brownell wrote:
> >
> > james anderson wrote:
> > >
> > > i had understood
> > >   {"","a",""},
> > > from the example, to denote a name in a namespace for which there would have
> > > been a declaration, namely a binding such as
> > >
> > >   <... xmlns="" ... >
> > >
> > > for the ignominious "null" namespace. how does this come to correspond to
> > >
> > >   { undeclared, "a", valid-prefix } ?
> >
> > It doesn't.  Namespace URIs clearly have three kinds of values, not that
> > it's specified in the namespace spec very clearly (and I suspect DOM L2
> > may need tweaking to get this right):
> >
> >         - Undeclared (null?)
> >         - Declared as no-value (empty string, "")
> >         - Some URI (the case folk focus on).
> 
> don't they have four?
>           - Undeclared (not "null"; that term already has a different meaning
> in the REC)
>           - Declared as "no namespace":      xmlns=""
>           - Declares as the empty string:    xmlns:html=""
>           - Some URI (the case folk focus on).
> 
> >
> > The distinction between "undefined" and "empty" will be familiar to folk
> > in the database world (maybe with different terms).  SAX2 will have to be
> > clear on how it exposes this.
> >
> > One more edge case for applications to trip over!
> >
> > - Dave
> >
> > > i agree that an "==" implementation needs to account for this, but didn't
> > > think it was nonconformant.
> > >
> > > David Brownell wrote:
> > > >
> > > > David Megginson wrote:
> > > > >
> > > > > Clark C. Evans writes:
> > > > >
> > > > >  > On Sun, 26 Dec 1999 uche.ogbuji@f... wrote:
> > > > >  > >
> > > > >  > > {"http://www.w3.org/1999/xhtml", "a", ""} ==
> > > > >  > > {"http://www.w3.org/1999/xhtml", "a", "html"}.
> > > > >  >
> > > > >  >          {"","a",""} != {"","a","html"}
> > > > >
> > > > > As I understood it, the suggestion was that
> > > > >
> > > > >   {"", "a", ""} == {"", "a", "html"}
> > > >
> > > > Actually I think the namespace spec defines
> > > >
> > > >     { undeclared, "a", valid-prefix }
> > > >
> > > > as "namespace-nonconformant", AKA some kind of error which they
> > > > neglected to describe well enough to support portable APIs.
> > > >
> > > > Meaning that any application choosing to use such a "Name"
> > > > class (which IMHO is a fine notion) needs to treat this value
> > > > with care ... IEEE floating point math has a variety of sorts
> > > > of "NaN" values, perhaps useful models can be found there.
> > > > I'd suggest that most "==" tests against such a Name ought to
> > > > fail, and ordering tests should cause exceptions.
> > > >
> > >
> 
> xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i...
> Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ and on CD-ROM/ISBN 981-02-3594-1
> To unsubscribe, mailto:majordomo@i... the following message;
> unsubscribe xml-dev
> To subscribe to the digests, mailto:majordomo@i... the following message;
> subscribe xml-dev-digest
> List coordinator, Henry Rzepa (mailto:rzepa@i...)

xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i...
Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ and on CD-ROM/ISBN 981-02-3594-1
To unsubscribe, mailto:majordomo@i... the following message;
unsubscribe xml-dev
To subscribe to the digests, mailto:majordomo@i... the following message;
subscribe xml-dev-digest
List coordinator, Henry Rzepa (mailto:rzepa@i...)



PURCHASE STYLUS STUDIO ONLINE TODAY!

Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced!

Buy Stylus Studio Now

Download The World's Best XML IDE!

Accelerate XML development with our award-winning XML IDE - Download a free trial today!

Don't miss another message! Subscribe to this list today.
Email
First Name
Last Name
Company
Subscribe in XML format
RSS 2.0
Atom 0.3
 

Stylus Studio has published XML-DEV in RSS and ATOM formats, enabling users to easily subcribe to the list from their preferred news reader application.


Stylus Studio Sponsored Links are added links designed to provide related and additional information to the visitors of this website. they were not included by the author in the initial post. To view the content without the Sponsor Links please click here.

Site Map | Privacy Policy | Terms of Use | Trademarks
Free Stylus Studio XML Training:
W3C Member
Stylus Studio® and DataDirect XQuery ™are products from DataDirect Technologies, is a registered trademark of Progress Software Corporation, in the U.S. and other countries. © 2004-2013 All Rights Reserved.