adding controller additions with basic behavior.

lib/cancan.rb

@@ -1,3 +1,8 @@
 $:.unshift(File.dirname(__FILE__))
-require 'cancan/ability'
 require 'cancan/instance_exec'
+require 'cancan/ability'
+require 'cancan/controller_additions'
+
+module CanCan
+  class AccessDenied < StandardError; end
+end

lib/cancan/controller_additions.rb

@@ -0,0 +1,23 @@
+module CanCan
+  module ControllerAdditions
+    def self.included(base)
+      base.helper_method :can?
+    end
+    
+    def unauthorized!
+      raise AccessDenied, "You are unable to access this page."
+    end
+    
+    def current_ability
+      ::Ability.for_user(current_user)
+    end
+    
+    def can?(*args)
+      (@current_ability ||= current_ability).can?(*args)
+    end
+  end
+end
+
+class ActionController::Base
+  include CanCan::ControllerAdditions
+end