> I think he means the fact that ivars don't throw name errors (or no
> method errors) if they haven't been assigned to yet, they just become
> nil by default.

That's right.

  class X
    def yelp!
      @yelpling
    end
  end

  X.new.yelp!   #=>  nil

Just invoking @yelping brings it into existence. You do not need to
assign it first, like you do local vars.

T.