XOM API for Processing XML with Java

[Laurent Bihanic <laurent.bihanic AT atosorigin.com>]

Elliotte Rusty Harold wrote:
> Also, one final asymmetry: Element has declareNamespace and 
> removeNamespaceDeclaration. Should this be declareNamespace and 
> undeclareNamespace? or addNamespaceDeclaration and 
> removeNamesapceDeclaration?

I'd prefer add/removeNamespaceDeclaration because it less imply that the 
actual namespace declaration will take place at this node in the serialized 
document. declareNamespace sounds like "I want the NS declaration to be place 
right here".

> The big concern for the declare and undeclare methods is what happens 
> when you attempt to declare or undeclare the namespace of that element 
> or one of its attributes? Should I throw an exception? no-op? Or should 
> I allow namespace declarations in the list of additional namespaces 
> which duplicate the namespaces of the element and its attributes, in 
> case the URI or prefix of the element or attribute is later changed?

When looked alone, the current implementation for add & remove looks fine, 
i.e.:
- you can only add NSs that do not conflict with the namespaces of the element 
and its attributes
- attempts to add duplicate namespaces are ignored
- attempts to remove the namespace of the element or one of its attributes are 
ignored (side effect due to that the namespace list contains only the 
additional namespaces)

What bothers me more here is the behaviour of the methods 
getNamespaceDeclarationCount() and getNamespacePrefix(): they do not give 
access to the element and attributes namespaces.

Hence, you can easily reach the following situation:
1. call e.addNamespaceDeclaration() to redeclare the NS of an attribute: OK
2. call e.getNamespaceURI(prefix): OK, youy get the NS URI
3. call e.getNamespaceDeclarationCount and a loop to gather all prefixes: You 
won't find the namespace you've just declared.

That is not quite a "consistent" behaviour! I'd expect to be able to find any 
namespace I've successfully added.

Thus, it may be better if add/remove throw some exceptions for duplicate 
namespace declarations.

Laurent