expose.rb

module Expose
  def expose(*methods)
    attr_reader *methods # for when you still only assign ivars in the action
    helper_method *methods
  end
end

ActionController::Base.extend Expose

index.html.erb

<% widgets.each do |widget| %>
  <p><%= widget.name %></p>
<% end %>

widgets_controller.rb

class WidgetsController < ApplicationController

  expose :widgets, :widget

  def index
  end

  private

  def widgets
    @widgets ||= Widget.all
  end

  def widget
    @widget ||= Widget.find(params[:id])
  end

end