[Fredrik Lundh]
>>can anyone perhaps dig up a DOM L2 implementation that's not written
>>by anyone involved in this thread, and see what it does ?
[Paul Boddie]
> document = libxml2dom.createDocument(None, "doc", None)
> top = document.xpath("*")[0]
> element = document.createElementNS("DAV:", "href")
> document.replaceChild(element, top)
> print document.toString()
>
> This outputs the following:
>
> <?xml version="1.0"?>
> <href xmlns="DAV:"/>
But that's incorrect. You have now defaulted the namespace to "DAV:" for
every unprefixed element that is a descendant of the href element.
Here is an example
#-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
document = libxml2dom.createDocument(None, "doc", None)
top = document.xpath("*")[0]
elem1 = document.createElementNS("DAV:", "href")
document.replaceChild(elem1, top)
elem2 = document.createElementNS(None, "no_ns")
document.childNodes[0].appendChild(elem2)
print document.toString()
#-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
which produces
"""
<?xml version="1.0"?>
<href xmlns="DAV:"><no_ns/></href>
"""
The defaulting rules of XML namespaces state
"""
5.2 Namespace Defaulting
A default namespace is considered to apply to the element where it is
declared (if that element has no namespace prefix), and to all elements
with no prefix within the content of that element.
"""
http://www.w3.org/TR/REC-xml-names/#defaulting
So although I have explicitly specified no namespace for the no_ns
subelement, it now defaults to the default "DAV:" namespace which has
been declared in the automagically created xmlns attribute. This is
wrong behaviour.
If I want for my sub-element to truly have no namespace, I have to write
it like this
"""
<?xml version="1.0"?>
<myns:href xmlns:myns="DAV:"><no_ns/></myns:href>
"""
[Paul Boddie]
> Leaving such
> attributes out by default, whilst claiming some kind of "fine print"
> standards compliance, is really a recipe for unnecessary user
> frustration.
On the contrary, once you start second guessing the standards and making
guesses about what users are really trying to do, and making decisions
for them, then some people are going to get different behaviour from
what they rightfully expect according to the standard. People whose
expectations match with the guesses made on their behalf will find that
their software is not portable between DOM implementations.
With something as finicky as XML namespaces, you can't just make ad-hoc
decisions as to what the user "really wants". That's why DOM L2 punted
on the whole problem, and left it to DOM L3.
--
alan kennedy
------------------------------------------------------
email alan: http://xhaus.com/contact/alan
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