adding model adapter files in proper location with loading behavior

Gemfile

@@ -1,10 +1,13 @@
 source "http://rubygems.org"
-gemspec
 
 case ENV["MODEL_ADAPTER"]
+when nil, "active_record"
+  gem "activerecord", :require => "active_record"
+when "data_mapper"
+  gem "dm-core", "~> 1.0.2"
 when "mongoid"
   gem "bson_ext", "~> 1.1"
   gem "mongoid", "~> 2.0.0.beta.19"
-when "data_mapper"
-  gem "dm-core", "~> 1.0.2"
 end
+
+gemspec

lib/cancan.rb

@@ -2,8 +2,10 @@ require 'cancan/ability'
 require 'cancan/rule'
 require 'cancan/controller_resource'
 require 'cancan/controller_additions'
-require 'cancan/active_record_additions'
-require 'cancan/mongoid_additions'
 require 'cancan/exceptions'
 require 'cancan/query'
 require 'cancan/inherited_resource'
+
+require 'cancan/model_adapters/active_record_adapter' if defined? ActiveRecord
+require 'cancan/model_adapters/data_mapper_adapter' if defined? DataMapper
+require 'cancan/model_adapters/mongoid_adapter' if defined? Mongoid

lib/cancan/model_adapters/data_mapper_adapter.rb

@@ -1,5 +1,3 @@
-require 'dm-core'
-
 module CanCan
   module Ability
     # could use alias_method_chain, but it's not worth adding activesupport as a gem dependency

spec/cancan/model_adapters/data_mapper_adapter_spec.rb

@@ -1,6 +1,5 @@
 if ENV["MODEL_ADAPTER"] == "data_mapper"
   require "spec_helper"
-  require 'cancan/data_mapper_additions'
 
   describe CanCan::DataMapperAdditions do
     before(:each) do

spec/cancan/model_adapters/mongoid_adapter_spec.rb

@@ -1,5 +1,4 @@
 if ENV["MODEL_ADAPTER"] == "mongoid"
-  require 'mongoid' # require mongoid first so MongoidAdditions are loaded
   require "spec_helper"
 
   class MongoidCategory
@@ -35,7 +34,7 @@ if ENV["MODEL_ADAPTER"] == "mongoid"
   end
 
   Mongoid.configure do |config|
-    config.master = Mongo::Connection.new('127.0.0.1', 27017).db("cancan_mongoid_additions_spec")
+    config.master = Mongo::Connection.new('127.0.0.1', 27017).db("cancan_mongoid_spec")
   end
 
   describe CanCan::MongoidAdditions do
@@ -50,7 +49,6 @@ if ENV["MODEL_ADAPTER"] == "mongoid"
       it "should not raise an error for ActiveRecord models" do
         @model_class = Class.new(Project)
         stub(@model_class).scoped { :scoped_stub }
-        @model_class.send(:include, CanCan::ActiveRecordAdditions)
         @ability = Object.new
         @ability.extend(CanCan::Ability)
           
@@ -60,7 +58,7 @@ if ENV["MODEL_ADAPTER"] == "mongoid"
         }.should_not raise_error
       end    
     end
-  
+
     context "Mongoid defined" do
       before(:each) do
         @model_class = MongoidProject

spec/spec_helper.rb

@@ -1,6 +1,8 @@
 require 'rubygems'
 require 'bundler/setup'
+
 Bundler.require(:default)
+
 require 'supermodel' # shouldn't Bundler do this already?
 require 'active_support/all'
 require 'matchers'