rails--rails/activesupport/CHANGELOG.md

• Introduce Concern#class_methods as a sleek alternative to clunky module ClassMethods. Add Kernel#concern to define at the toplevel without chunky module Foo; extend ActiveSupport::Concern boilerplate.

  # app/models/concerns/authentication.rb
  concern :Authentication do
    included do
      after_create :generate_private_key
    end
  
    class_methods do
      def authenticate(credentials)
        # ...
      end
    end
  
    def generate_private_key
      # ...
    end
  end
  
  # app/models/user.rb
  class User < ActiveRecord::Base
    include Authentication
  end
  

  Jeremy Kemper

Please check 4-1-stable for previous changes.