Brian,

There’s no need to make the methods private. I address the choice, though:

What? [controller.#{helper_method} is] pretty ugly? And what about the controller public instance methods? They should refer to actions? I guess we can’t completely ignore Rails’ conventions. We’ll have to make those getters private. But how, now, can we deliver these methods to the view? Luckily, Rails makes this easy with helpers.

Basically, that choice is just to conform to some Rails conventions. If you think about it, helper_method is just something that makes methods public to the view. Not unlike:

private
  def test; "test" end

public :test

The entire article was meant as an exercise and halfway proof-of-concept. Regardless, it had a few nice side-effects: using helper methods basically delays the method calls so that if you are caching you don’t have needless database queries, and you don’t have to waste time scoping and maintaining your instance variable-setting before_filters. For these reasons alone I don’t think my minor concession to convention is “defeating [my] point.”

...but just remember that the helper_method isn't making methods "public" to the view...

Yes. That was a poor choice of words. I was just trying to make an analogy. There is certainly more going on behind the scenes; It’s just a question of explicitness.

@articles, set in a controller and seemingly just available in the view, is less explicit than calling helper_method to send methods to the view.

Mike, feel free to email me with more detail on the subject (there’s a link on the bottom of my site).

Generally, using a helper method instead of an instance variable should yield identical results; the difference may arise, I suppose, is if you let instance variables silently fail if they aren’t populated. I think the preferred practice would be to seek out these RecordNotFound exception-raisers, and make sure that record should be available for the current action.

An alternative would be to call Model.find_by_id(params[:id]) instead of Model.find(params[:id]).

There are, likely, some core Rails methods that assume instance variables are being used (error_messages_for being one of them, I believe), but there are usually workarounds (f.error_messages in a form_for, for example).