From: Chris Morris <home@...>
Date: 2002-04-10T14:22:18+09:00
Subject: RE: ruby + Creating and extending XML documents

> I`m pretty new to Object Orientation, so am I being naive?
> Is my approach totally off the mark?

I think you've got a good grasp of the benefits of inheritence. You've put
the portions that pertain to all documents in a base class, and limited the
portions that are more limited in scope to a descendant class.

One potential problem: you are coupling your raw data (title, user, etc.)
with its storage/presentation in xml. For example, I can add a user to the
MasterDocument, but I can't retrieve it same as I put it in, I can only
retrieve an xml representation of it. I think if you go much farther
feature-wise with your code, you might quickly see the need to decouple the
basic data from its xml representation. Then again, it's probably working
fine for now, and if that's good enough, it's probably good enough.

I'll also plug a project I've been cobbling together. It's a module called
XmlSerialization that would allow you to recode your class this way:

  class MasterDocument
    include XmlSerialization

    attr_accessor :title, :user
  end

... and you can essentially do this still:

xml = MasterDocument.new
xml.title = "A Page On My Site"
xml.user  = user
# puts xml.document
xml.to_xml.write(io)

This also allows you to work with the title and user data directly,
decoupling the data from its xml rep.

You can check it out here: http://clabs.org/clxmlserial.htm. Still in a
prerelease stage, but it's functional, I use it in production code on the
job.

> Have I been smoking too many drugs?

More than none is probably too many.

Chris