Use ActiveSupport::Concern.

lib/devise/controllers/helpers.rb

@@ -2,9 +2,9 @@ module Devise
   module Controllers
     # Those helpers are convenience methods added to ApplicationController.
     module Helpers
+      extend ActiveSupport::Concern
 
-      def self.included(base)
-        base.class_eval do
+      included do
         helper_method :warden, :signed_in?, :devise_controller?,
                       *Devise.mappings.keys.map { |m| [:"current_#{m}", :"#{m}_signed_in?"] }.flatten
 
@@ -14,7 +14,6 @@ module Devise
           Devise::Mapping.default_url_options
         end
       end
-      end
 
       # The main accessor for the warden proxy instance
       def warden

lib/devise/models/authenticatable.rb

@@ -27,14 +27,12 @@ module Devise
     #    User.find(1).valid_password?('password123')         # returns true/false
     #
     module Authenticatable
-      def self.included(base)
-        base.class_eval do
-          extend ClassMethods
+      extend ActiveSupport::Concern
 
+      included do
         attr_reader :password, :current_password
         attr_accessor :password_confirmation
       end
-      end
 
       # Regenerates password salt and encrypted password each time password is set,
       # and then trigger any "after_changed_password"-callbacks.

lib/devise/models/confirmable.rb

@@ -29,16 +29,13 @@ module Devise
     #   User.find(1).send_confirmation_instructions # manually send instructions
     #   User.find(1).resend_confirmation! # generates a new token and resent it
     module Confirmable
+      extend ActiveSupport::Concern
       include Devise::Models::Activatable
 
-      def self.included(base)
-        base.class_eval do
-          extend ClassMethods
-
+      included do
         before_create :generate_confirmation_token, :if => :confirmation_required?
         after_create  :send_confirmation_instructions, :if => :confirmation_required?
       end
-      end
 
       # Confirm a user by setting it's confirmed_at to actual time. If the user
       # is already confirmed, add en error to email field

lib/devise/models/http_authenticatable.rb

@@ -6,9 +6,7 @@ module Devise
     # model class responds to authenticate and authentication_keys methods
     # (which for example are defined in authenticatable).
     module HttpAuthenticatable
-      def self.included(base)
-        base.extend ClassMethods
-      end
+      extend ActiveSupport::Concern
 
       module ClassMethods
         # Authenticate an user using http.

lib/devise/models/lockable.rb

@@ -18,14 +18,9 @@ module Devise
     #              available when unlock_strategy is :time or :both.
     #
     module Lockable
+      extend ActiveSupport::Concern
       include Devise::Models::Activatable
 
-      def self.included(base)
-        base.class_eval do
-          extend ClassMethods
-        end
-      end
-
       # Lock an user setting it's locked_at to actual time.
       def lock
         self.locked_at = Time.now

lib/devise/models/recoverable.rb

@@ -14,11 +14,7 @@ module Devise
     #   # creates a new token and send it with instructions about how to reset the password
     #   User.find(1).send_reset_password_instructions
     module Recoverable
-      def self.included(base)
-        base.class_eval do
-          extend ClassMethods
-        end
-      end
+      extend ActiveSupport::Concern
 
       # Update password saving the record and clearing token. Returns true if
       # the passwords are valid and the record was saved, false otherwise.

lib/devise/models/rememberable.rb

@@ -30,15 +30,12 @@ module Devise
     #   # lookup the user based on the incoming cookie information
     #   User.serialize_from_cookie(cookie_string)
     module Rememberable
+      extend ActiveSupport::Concern
 
-      def self.included(base)
-        base.class_eval do
-          extend ClassMethods
-
+      included do
         # Remember me option available in after_authentication hook.
         attr_accessor :remember_me
       end
-      end
 
       # Generate a new remember token and save the record without validations.
       def remember_me!

lib/devise/models/timeoutable.rb

@@ -11,9 +11,7 @@ module Devise
     #
     #   timeout_in: the time you want to timeout the user session without activity.
     module Timeoutable
-      def self.included(base)
-        base.extend ClassMethods
-      end
+      extend ActiveSupport::Concern
 
       # Checks whether the user session has expired based on configured time.
       def timedout?(last_access)

lib/devise/models/token_authenticatable.rb

@@ -18,12 +18,11 @@ module Devise
     #    User.find(1).valid_authentication_token?('rI1t6PKQ8yP7VetgwdybB')  # returns true/false
     #
     module TokenAuthenticatable
-      def self.included(base)
-        base.class_eval do
-          extend ClassMethods
+      extend ActiveSupport::Concern
+
+      included do
         before_save :ensure_authentication_token
       end
-      end
 
       # Generate new authentication token (a.k.a. "single access token").
       def reset_authentication_token