API Versioning and Inheritance

gistfile1.rb

module API
  module V1
    class UsersController
      def index
        'v1'
      end
      def show
        'v1'
      end
    end

    class PostsController
      def index
        'v1'
      end
    end
  end

  module V2
    include V1

    class UsersController < UsersController
      def index
        'v2'
      end
    end
  end

  module V3
    include V2

    class UsersController < UsersController
      def index
        'v3'
      end

      undef_method :show
    end

    class PostsController < PostsController
      def show
        'v3'
      end
    end
  end
end

(1..3).each do |i|
  puts "Version #{i}"
  puts '========='
  [:UsersController, :PostsController].each do |klass|
    puts klass
    instance = API.const_get("V#{i}").const_get(klass).new
    puts "\tindex: #{instance.index rescue 'undefined'}"
    puts "\tshow:  #{instance.show  rescue 'undefined'}"
    puts
  end
end

# Version 1
# =========
# UsersController
#   index: v1
#   show:  v1
#
# PostsController
#   index: v1
#   show:  undefined
#
# Version 2
# =========
# UsersController
#   index: v2
#   show:  v1
#
# PostsController
#   index: v1
#   show:  undefined
#
# Version 3
# =========
# UsersController
#   index: v3
#   show:  undefined
#
# PostsController
#   index: v1
#   show:  v3