From: Holden Glova <dsafari@...>
Date: 2002-08-11T18:19:19+09:00
Subject: To be a Module, or not to be...

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Hello folks,

I am attempting to write a transparent persistence framework and am having a 
hard time deciding if something should be a class or it should be a module. 
The reason I would like it to be a module is because I am trying to write a 
framework where I do not want to interfere with the object model used by 
clients of the framework. Ideally they would just include my module and get 
my functionality for free thus making persistence even more transparent.

Where I get confused is that this module needs to set some instance variable 
state and initialize those variables. I would like it if there was a way for 
the state to be set after the the client object has been initialized? If that 
is not possible, or possibly not the best way to do it then please let me 
know.

Here is some code:
#
# Encapsulates the behavior needed to make objects persistent and is the 
module
# all classes wishing to be persisted should mix this in.
#
module ROS
module Persistable

  def initialize
    # I want these variables to be instance vars.
    @is_persistent = false
    @timestamp     = null
  end

  def retrieve
    ...
  end

  def save
    ...
  end


  def delete
    ...
  end

end
end

Many thanks in advance for any help offered.

- -- 
Signed,
Holden Glova
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