Alternative to Rails' sharing of instance variables between controller and views.

application_controller.rb

class ApplicationController < ActionController::Base
  # Creates an accessor which is exposed to the view
  def self.view_accessor(*names)
    attr_accessor *names
    helper_method *names
  end
end

articles_controller.rb

class ArticlesController < ApplicationController
  # List the variables/methods you want to expose to the view
  view_accessor :article, :articles
  
  def index
    # Assign the variable in the action
    self.articles = Article.all
  end
  
  def show
  end
  
  protected
  
  # Or implement directly as a method
  def article
    Article.find(params[:id])
  end
end

index.html.haml

%h1 Articles
-# Simply call the articles method instead of the instance variable.
- articles.each do |article|
  %article
    %h1.title= article.title

z_articles_controller_spec.rb

require 'spec_helper'

# Easy to test as well.

describe ArticlesController do
  describe "index" do
    let!(:articles) { create_list :article, 3 }
    
    it "assigns all the articles" do
      get :index
      controller.articles.should == articles
    end
  end
end

Nice work! Here's what I think this could look like as a gem: https://github.com/invisiblefunnel/view_accessor.

What is wrong with using @articles or @article?

@ka8725 "Bare words" references to data in the views would be better, because if you decided at some later date to change what was just an accessor to a method call, or something, you would still not have to refactor any of the views. Also, it lends itself to being more easily able to extract a partial from a given piece of view code, that would use bare words to access the local parameters, as opposed to instance variables of the controller. Avdi Grimm did a good video explaining the finer points here

Thanks @dolan , that makes perfectly logical sense!