define_callbacks (ActiveSupport::Callbacks::ClassMethods)

    # File lib/active_support/callbacks.rb, line 210
          def define_callbacks(*callbacks)
            callbacks.each do |callback|
              class_eval "def self.\#{callback}(*methods, &block)\ncallbacks = CallbackChain.build(:\#{callback}, *methods, &block)\n(@\#{callback}_callbacks ||= CallbackChain.new).concat callbacks\nend\n\ndef self.\#{callback}_callback_chain\n@\#{callback}_callbacks ||= CallbackChain.new\n\nif superclass.respond_to?(:\#{callback}_callback_chain)\nCallbackChain.new(superclass.\#{callback}_callback_chain + @\#{callback}_callbacks)\nelse\n@\#{callback}_callbacks\nend\nend\n"
            end
          end