Nano Enum v3

nano_enum.rb

module NanoEnum
  class << self
    def included(base)
      base.extend(ClassMethods)
    end
  end

  module ClassMethods
    def enum(*members)
      if members.first.is_a?(Hash)
        member_values = members.first.values
        iterator = members.first.each_pair
      else
        member_values = members.each_index.to_a
        iterator = members.each_with_index
      end

      klass = Class.new(Integer)

      klass.instance_eval <<-CODE, __FILE__, __LINE__ + 1
        def include?(value)
          #{member_values}.include?(value)
        end

        def to_a
          #{member_values}
        end
      CODE

      iterator.each do |member, value|
        klass.const_set(member.to_s.upcase, value)
      end

      klass
    end
  end
end

if $0 == __FILE__
  require 'mongoid'

  class Model
    include Mongoid::Document
    include NanoEnum

    TYPE = enum :apple => 15, :orange => 16

    field :type, :type => TYPE, :default => TYPE::ORANGE
    #field :type, :type => Integer, :default => TYPE::ORANGE
    validates_inclusion_of :type, :in => TYPE
  end

  puts Model::TYPE.superclass.name
    
  model = Model.new
  puts model.valid?
  puts model.inspect

  model.type = Model::TYPE::APPLE
  puts model.valid?
  puts model.inspect

  model.type = 13
  puts model.valid?
  puts model.inspect
  puts model.errors.full_messages
end