foo_controller.rb

class FooController < ApplicationController
  #
  # Each "------ N" is a step of refactoring. I start with 0 and go as far as I need to
  # depending on the code smell. Each step makes the code easier to reuse outside the view,
  # controller, etc.

  # ------ 0. Code smell, ivar
  def some_action
    @calculated_data = Something.funky.that('isnt').abstracted('in a lower level')
  end
  # View: <%= h @calculated_data %>
  
  # ------ 1. helper_method
  def some_action
  end
  
  private # << I'm not sure if private/protected for helper_method. Double check.
  def calculated_data
    Something.funky.that('isnt').abstracted('in a lower level')
  end
  helper_method :calculated_data
  
  # View: <%= h calculated_data %>
  
  # ------ 2. Helper
  def some_action
  end
  
  # In app/helpers/
  module FooHelper
    def calculated_data
      Something.funky.that('isnt').abstracted('in a lower level')
    end
  end
  
  # View:  <%= h calculated_data %>
  
  # ------ 3. Class
  def some_action
  end
  
  # in app/models or lib/ or someplace in load path
  class CalculatedSomething
    def self.calculate
      Something.funky.that('isnt').abstracted('in a lower level')
    end
  end
  
  # View: <%= h CalculatedSomething.calculate %>

end