Question

As the application grows, I’m starting to use a Presenter Pattern similar to what’s outlined here:

http://blog.jayfields.com/2007/03/rails-presenter-pattern.html

I would like the presenter to be able to access the same scope of the controller it’s in, in a way that minimally impacts application performance, and that has a clear API. Something like this:

class UsersController < ApplicationController
  def index
    @view = UsersPresenter.new(self)
  end
end

class Presenter
  def initialize(controller)

  end
end

class UsersPresenter < Presenter

end

I could use method_missing to access methods on the controller but that comes at a performance cost, and would probably be confusing to debug:

class Presenter
  attr_reader :controller

  def initialize(controller)
    @controller = controller
  end

  def method_missing(method, *args, &block)
    controller.send(method, *args, &block)
  end
end

I would like it to work just like a module, but without being a module so I don’t clutter the global controller namespace.

Any ideas what’s best here? Maybe the delegate method?

Thanks for the tips.

Answer 1

An approach to work around method_missing: Enumerate all instance methods of the controller and define methods in the eigenclass of your presenter (in the initializer). However I doubt that it’s better performance-wise when compared to method_missing.

Also this won’t work for methods that were added to the controller via method_missing (like polymorphic routes).

I don’t think that you can work around the method_missing completely if you want access to all the (missing) methods of the controller without explicitly writing controller.some_method in your presenter.