game.rb

module Presenters
  class Game
    include Presenter
    def initialize(game)
      @game = game
      self
    end

    def prepare
      generate_messages
    end

    def generate_messages
      unless @player
        @join_message = @leave_message = nil
        @create_message = "Erstelle zuerst einen Player <hier>."
      end
    end

    def default
      @template = "games/presenters/#{template_for_state(@game.state)}"
      self
    end

    def widget
      @template = "games/presenters/widget/#{template_for_state(@game.state)}"
      self
    end

    private
    def template_for_state(state)
      templates = Hash.new {|h,k| k }
      templates.merge({
        "scourge_won" => "finished",
        "sentinel_won" => "finished",
      })
      templates[state]
    end

  end
end

presenters.rb

require "rango/mixins/rendering"

module Presenters
  module Mixin
    def present(type=:default)
      Presenters.present(self, type)
    end
  end

  def present(model, type)
    const_get(model.class.to_s).new(model).send(type)
  end

  module_function :present
end

module Presenter
  include Rango::ImplicitRendering
  include Rango::Helpers

  def to_s
    prepare if respond_to? :prepare
    render @template
  end

  def with(hash)
    hash.each {|k,v| instance_variable_set("@#{k}", v) }
    self
  end
end

%w(game).each {|file| require_relative("presenters/" + file)}