Null object pattern for User as GuestUser

app/controllers/application_controller.rb

@@ -10,9 +10,10 @@ class ApplicationController < ActionController::Base
 
   def current_user
     @current_user ||= User.find(session[:user_id]) if session[:user_id]
+    @current_user ||= GuestUser.new
   end
 
   def logged_in?
-    @logged_in ||= !!current_user
+    @logged_in ||= current_user.class.name.demodulize == 'User'
   end
 end

app/models/user.rb

@@ -26,3 +26,13 @@ class User < ActiveRecord::Base
     self.add_role :admin
   end
 end
+
+class GuestUser
+  def admin?
+    false
+  end
+
+  def moderator?
+    false
+  end
+end