[jdom-interest] Namespace inheritance after cloning

[Jason Hunter]

Off topic but related to the namespace idea, one thing I've found is 
there's no efficient way to have "modes" like you're talking about that 
apply at construction time.

Statics are global to a class loader and thus aren't real appropriate in 
a J2EE environment where different people may use JDOM with the same 
class loader.  Thread local variables are slow.  This is why J2EE uses 
factories *so* much, and makes modes an aspect of the factory.

We faced the issue when trying to have a mode to turn off verification. 
  In the end we implemented a factory-based solution.

-jh-

Per Norrman wrote:
> Hi,
> I've been harbouring (spelling?) an idea where there were two distinct
> modes of Element/Attribute creation. One namespace unaware, in which it 
> would be impossible to create Elements in any namespace but 
> NO_NAMESPACE; and one namespace aware mode, where it would be impossible 
> to create Elements without
> explicitly declaring their namespace. Lot's of headaches would be 
> alleviated.
> 
> Not sure how to solve it though, except a Design Rule: When dealing with
> namespaces, ALWAYS use the namespace enabled constructors.
> 
> /pmn
> 
> Jason Hunter wrote:
> 
>> Alistair Young wrote:
>>
>>> I have a strange problem. I've read the archives and the FAQ and
>>> understand the non inheritance of prefix:local style namespaces. 
>>> However,
>>> when I do:
>>>
>>> Document root =
>>> <root xmlns="http://test.ns">
>>> </root>
>>>
>>> Document next =
>>> <next>some text</next>
>>>
>>> root.getRootElement().addContent((Content)next.getRootElement().clone()); 
>>>
>>>
>>> I get:
>>> <root xmlns="http://test.ns">
>>>   <next xmlns="">some text</next>
>>> </root>
>>>
>>> and it breaks the XML schema validation! <next> should obviously be 
>>> in the
>>> test.ns namespace. JDOM seems to want to put it in an empty namespace.
>>
>>
>>
>> The <next> you created is in no namespace.  When you move it to 
>> another document, the element doesn't change namespaces.  Namespaces 
>> are an intrinsic part of each Element and don't depend on placement.  
>> So on output JDOM has to make sure that the default namespace on 
>> <root> doesn't mistakenly apply to <next> so it writes xmlns="" which 
>> reassigns the default namespace for that context to no namespace.  
>> JDOM's correctly serializing the XML data model as you created it.
>>
>>> Now, the weird thing is, if I create <next> with the same namespace as
>>> <root>, JDOM still replaces it with xmlns="".
>>
>>
>>
>> That's not something JDOM would do.  I suspect your code isn't 
>> actually doing what you describe here.  :)  If you can't figure it 
>> out, send in a simple code sample showing the issue and we'll see if 
>> it's any real bug.
>>
>>> If <root> doesn't have a namespace, then the xmlns="" isn't added to 
>>> <next>.
>>> Nowhere in the code is xmlns="" generated when creating the <next> 
>>> Element.
>>
>>
>>
>> Right, because there's no need to redefine the default namespace when 
>> there's no default namespace in effect.
>>
>> -jh-
>>
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> 
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