[jdom-interest] Design Patterns

Trimmer, Todd todd.trimmer at trizetto.com
Wed May 2 13:23:53 PDT 2001

You basically stated my assumption was wrong and then proceeded to give your
own interpretation that was exact assumption in different words. Weird :/

Visitable *is* the underlying interface in this case.

I'd rather have a Node interface, so that we can make both Visitors and
Decorators easier to implement.

Still, I see don't see who is responsible for walking the tree, I only see
how we can manipulate a Node, once there.

Todd Trimmer

-----Original Message-----
From: Frank Sauer <Frank.Sauer at trcinc.com>
To: "'jdom-interest at jdom.org'" <jdom-interest at jdom.org>
Subject: RE: [jdom-interest] Design Patterns
Date: Wed, 2 May 2001 13:15:08 -0400 

I think you're mistaken there. All that the visitor
pattern requires is that all objects being visited
implement some kind of Visitable interface accepting
a Visitor (interface) in some kind of a visit method.
This does not require a common base class and each class
being visited can have completely different implementations
of the visit method. Personally I think a Visitor pattern
could be the answer to the tree walking issues in relation to
this common Node discussion.

Frank Sauer
The Technical Resource Connection, Inc.
a wholly owned subsidiary of Perot Systems
Tampa, FL
Java: The best argument for Smalltalk since C++

-----Original Message-----
From: Trimmer, Todd [mailto:todd.trimmer at trizetto.com]
Sent: Wednesday, May 02, 2001 12:05 PM
To: 'jdom-interest at jdom.org'
Subject: [jdom-interest] Design Patterns

More than one request to add functionality has been responded with "Use a
Decorator for this" or "Use a Visitor for that."

Both of these patterns assume a base class for a hierarchy of objects to be
acted upon. Does anyone realize how much harder these patterns are to
implement without an underlying interface? Wouldn't Node solve this problem?

Todd Trimmer

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