[jdom-interest] Element Reference from Attribute

[Jerry Lawson]

In the words of Homer (Simpson, not the poet): woohoo!
I really like James' approach. Very simply, very elegant, and
very extensible. How's about it Jason ?

James Strachan wrote:

> ----- Original Message -----
> From: "Jason Hunter" <jhunter at collab.net>
> > James Strachan wrote:
> > As I've said earlier, I think SAXBuilder should be designed to be easily
> > subclassed with protected createElement() style methods which can be
> > intricately tied to the information SAXBuilder has, rather than try to
> > make a generic plug-in factory model a la
> > setElementFactory(ElementFactory).
>
> <pedant>
> Its the SAXHandler that needs these methods, as creates the Element /
> Attribute objects. So you actually need to subclass SAXHandler and also
> SAXBuilder, to create your new SAXHandler derivation.
> </pendant>
>
> > I think the subclass route has more power, and keeps us from needing six
> > new *Factory classes.
>
> I hear you and agree. I've posted to this list twice today a refactored
> SAXBuilder / SAXHandler that does exactly this. I'm still waiting for it to
> show up on the list though :-(
>
> Deriving from SAXBuilder and SAXHandler to implement this kinda
> functionality is OK.
>
> However I'm warming to the idea of having a single SAXFactory class with all
> the factory methods in it that SAXHandler requires together in one class
> together with default implementations (createElement(), createAttribute,
> etc.). Then just a single factory class needs to be subclassed to get the
> behaviour people need. It is likely that if a user wants to do some custom
> building, they may want to create more than just custom Elements, they may
> want something else too (Attribute, Entity, CDATA, Namespace or whatever) so
> it would make things simpler and easier to keep the factory methods in one
> class.
>
> So the only API change would be something like the following... (I've
> included a default Singleton pattern into the implementation, to keep the
> perfomance obsessives folk happy ;-)
>
> public class SAXBuilder {
>     private SAXFactory factory;
>
>     /** Default singleton implementation */
>     private static final SAXFactory defaultFactory = new SAXFactory();
>
>     public void setFactory(SAXFactory factory) {
>         this.factory = factory;
>     }
>
>     public SAXFactory getFactory() {
>         if ( factory == null ) {
>             return defaultFactory;
>         }
>         return factory;
>     }
>
>     ...
> }
>
> /** Default factory used by SAXBuilder / SAXHandler to
>   * create JDOM objects from a SAX event stream
>   */
> public class SAXFactory {
>
>     public Element createElement(String localName, Namespace
> elementNamespace) {
>         return new Element( localName, elementNamespace );
>     }
>     public Element createElement(String localName) {
>         return new Element(localName);
>     }
>
>     public Attribute createAttribute(Element element, String attLocalName,
> String value, Namespace attNamespace) {
>         return new Attribute(attLocalName, value, attNamespace);
>     }
>
>     public Attribute createAttribute(Element element, String attLocalName,
> String value) {
>         return new Attribute(attLocalName, value);
>     }
>
>     public ProcessingInstruction createProcessingInstruction(String target,
> String data) {
>         return new ProcessingInstruction(target, data);
>     }
>
>     public CDATA createCDATA(String data) {
>         return new CDATA(data);
>     }
>
>     public DocType createDocType(String name, String publicId, String
> systemId) {
>         return new DocType(name, publicId, systemId);
>     }
>
>     public Entity createEntity(String name) {
>         return new Entity(name);
>     }
>
>     public Comment createComment(String commentText) {
>         return new Comment(commentText);
>     }
> }
>
> J.
>
> James Strachan
> =============
> email: james at metastuff.com
> web: http://www.metastuff.com
>
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--
___________________________________________________
Jerry Lawson                   Virtual Summit, Inc.
Virtual Programmer   jerry.lawson at virtualsummit.com