presenter.rb

require 'delegate'

module Presenter
  def presenter
    presenter = "#{self.class.name}Presenter".constantize
    presenter.new(self)
  end

  # Example of usage:
  #
  #   class PersonPresenter < Presenter::Proxy
  #     def full_name
  #       "#{last_name}, #{first_name}"
  #     end
  #   end
  #
  #   person = Person.new(:first_name => "Gabriel", :last_name => "Sobrinho")
  #   person.presenter.full_name #=> "Sobrinho, Gabriel"
  class Proxy < SimpleDelegator
  end
end

class ActiveRecord::Base
  include Presenter
end