Rails lookup v2 - Create the lookup type

gistfile1.rb

    def lookup(as_name)
      mycls = self #Class I'm defined in
 
      #We now define the CarType class, as if we were in a file car_type.rb
      cls = Class.new(ActiveRecord::Base) do #Define a new class, extending AR::Base
        #CarType should have the has_many :cars link
        has_many mycls.name.tableize.to_sym

        #These are optional. You can define any additional constraints you like.
        validates_uniqueness_of :name
        validates :name, :presence => true

        #Methods for using the cache. Providing a second argument saves data into the cache.
        def self.id_for(name, id = nil)
          #We cannot access the class variable for CarType as simply '@@rcaches' because it will
          #look for @@rcaches in the scope of the module we're in.
          class_variable_get(:@@rcaches)[name] ||= id
        end

        #This helper method is the "find_or_create" of the class that also
        #updates the cache and the DB.
        def self.gen_id_for(val)
          id = id_for val
          if id.nil?
            #Define this new possible value
            new_db_obj = find_or_create_by_name val
            id_for val, new_db_obj.id
            name_for new_db_obj.id, val
            id = new_db_obj.id
          end
          id
        end

        #Query the cache for the value that goes with a certain DB ID
        def self.name_for(id, name = nil)
          class_variable_get(:@@caches)[id] ||= name
        end
      end

      #Finally, Bind the created class to a name
      lookup_cls_name = lookup_name.to_s.camelize
      Object.const_set lookup_cls_name, cls #Define it as a global class