moving can definition into ability instance instead of class, this removes ugly instance_exec command

lib/cancan/ability.rb

@@ -2,15 +2,8 @@ module CanCan
   module Ability
     attr_accessor :user
     
-    def self.included(base)
-      base.extend ClassMethods
-      base.alias_action :index, :show, :to => :read
-      base.alias_action :new, :to => :create
-      base.alias_action :edit, :to => :update
-    end
-    
     def can?(original_action, target) # TODO this could use some refactoring
-      (self.class.can_history || []).reverse.each do |can_action, can_target, can_block|
+      (@can_history || []).reverse.each do |can_action, can_target, can_block|
         possible_actions_for(original_action).each do |action|
           if (can_action == :manage || can_action == action) && (can_target == :all || can_target == target || target.kind_of?(can_target))
             if can_block.nil?
@@ -20,7 +13,7 @@ module CanCan
               block_args << action if can_action == :manage
               block_args << (target.class == Class ? target : target.class) if can_target == :all
               block_args << (target.class == Class ? nil : target)
-              return instance_exec(*block_args, &can_block)
+              return can_block.call(*block_args)
             end
           end
         end
@@ -30,32 +23,33 @@ module CanCan
     
     def possible_actions_for(initial_action)
       actions = [initial_action]
-      (self.class.aliased_actions || []).each do |target, aliases|
+      (@aliased_actions || default_alias_actions).each do |target, aliases|
         actions += possible_actions_for(target) if aliases.include? initial_action
       end
       actions
     end
+      
+    def can(action, target, &block)
+      @can_history ||= []
+      @can_history << [action, target, block]
+    end
     
-    module ClassMethods
-      attr_reader :can_history
-      attr_reader :aliased_actions
-      
-      def can(action, target, &block)
-        @can_history ||= []
-        @can_history << [action, target, block]
-      end
-      
-      def alias_action(*args)
-        @aliased_actions ||= {}
-        target = args.pop[:to]
-        @aliased_actions[target] = args
-      end
-      
-      def for_user(user)
-        ability = new
-        ability.user = user
-        ability
-      end
+    def alias_action(*args)
+      @aliased_actions ||= default_alias_actions
+      target = args.pop[:to]
+      @aliased_actions[target] = args
+    end
+    
+    def default_alias_actions
+      {
+        :read => [:index, :show],
+        :create => [:new],
+        :update => [:edit],
+      }
+    end
+    
+    def prepare(user)
+      # to be overriden by included class
     end
   end
 end