XOM API for Processing XML with Java

[Elliotte Rusty Harold <elharo AT metalab.unc.edu>]

At 10:33 AM +0200 9/19/02, Laurent Bihanic wrote:


>  - Code compactness: As I already said on the jdom-interest mailing 
> list, there are cases (e.g. TreeNode.getChild()) where instanceof 
> tests make the code very unclear and thus harder to maintain.
> I know Elliotte does not like the idea of a int getNodeType() method 
> but we need to find a way to remove these ugly tests.


I agree the situation is imperfect. I think there's a bit of a 
mismatch between the XML model and the Java model, but I don't see 
how we can do any better than I've done.

Why would

if (node.getNodeType() == Node.ELEMEBT_TYPE)

be preferable to

if (node instanceof Element)

?

They're both ugly. I think the second one is less ugly. With 
getNodeType() you could call it once at the top of the tree:

int type = node.getNodeType();
if (type == Node.ELEMENT_TYPE) ...
else if (type == Node.TEXT_TYPE) ...

but I still think the instanceof approach looks at least as clean and 
arguably cleaner. Int types would also allow switch statements, but 
that's even uglier and less clear for at most a very minor 
performance optimization.

Do you see something different? What do you think the code should 
look like? (Actually what I think the code should look like is 
polymorphic method dispatching, where I can pass a Node to a 
process() method and have the runtime choose the overloaded method to 
dispatch based on the node's subtype, but that's not a feature Java 
gives us so we have to deal. :-( )
--

+-----------------------+------------------------+-------------------+
| Elliotte Rusty Harold | elharo AT metalab.unc.edu | Writer/Programmer |
+-----------------------+------------------------+-------------------+
|          XML in a  Nutshell, 2nd Edition (O'Reilly, 2002)          |
|              http://www.cafeconleche.org/books/xian2/              |
|  http://www.amazon.com/exec/obidos/ISBN%3D0596002920/cafeaulaitA/  |
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