From: Sean O'Halpin <sean.ohalpin@...>
Date: 2008-03-09T08:12:59+09:00
Subject: ANN: doodle 0.0.1

Doodle is a Ruby library and gem for simplifying the definition of
Ruby classes by making attributes and their properties more
declarative.

Doodle is eco-friendly – it does not globally modify Object, Class or
Module, nor does it pollute instances with its own instance variables
(i.e. it plays nice with yaml). Future versions will try to be even
more unobtrusive.

It is similar to but different from libraries such as Ara Howard's
attributes and traits and likewise owes something to the famous
metakoans Ruby quiz.

Features:

    * initialization
          o using positional arguments
          o with named arguments
          o by block
    * defaults
    * initial values
    * validation at attribute and class levels
    * conversions for attributes and classes
    * collectors to help in defining simple DSLs
    * works for classes, instances and singletons

Putting all this together, you can initialize objects like this:

  event = Event "Festival" do
    date '2008-04-01'
    place "The muddy field"
    place "Beer tent" do
      event "Drinking"
    end
  end

  pp event

  #<Event:0x595394
   @date=#<Date: 4909115/2,0,2299161>,
   @locations=
    [#<Location:0x5913d4 @events=[], @name="The muddy field">,
     #<Location:0x58ef58
      @events=[#<Event:0x58d630 @locations=[], @name="Drinking">],
      @name="Beer tent">],
   @name="Festival">

from a class definition like this:

  require 'date'
  require 'pp'
  require 'doodle'

  class Location < Doodle::Base
    has :name, :kind => String
    has :events, :init => [], :collect => :Event
  end

  class Event < Doodle::Base
    has :name, :kind => String
    has :date do
      kind Date
      default { Date.today }
      must 'be >= today' do |value|
        value >= Date.today
      end
      from String do |s|
        Date.parse(s)
      end
    end
    has :locations, :init => [], :collect => {:place => "Location"}
  end

To install:

$ sudo gem install doodle

or

C:\> gem install doodle

For more info, see http://doodle.rubyforge.org/