instance method define_attribute_methods

# File activerecord/lib/active_record/attribute_methods.rb, line 38
      def define_attribute_methods
        unless defined?(@attribute_methods_mutex)
          msg = "It looks like something (probably a gem/plugin) is overriding the " \
                "ActiveRecord::Base.inherited method. It is important that this hook executes so " \
                "that your models are set up correctly. A workaround has been added to stop this " \
                "causing an error in 3.2, but future versions will simply not work if the hook is " \
                "overridden. If you are using Kaminari, please upgrade as it is known to have had " \
                "this problem.\n\n"
          msg << "The following may help track down the problem:"

          meth = method(:inherited)
          if meth.respond_to?(:source_location)
            msg << " #{meth.source_location.inspect}"
          else
            msg << " #{meth.inspect}"
          end
          msg << "\n\n"

          ActiveSupport::Deprecation.warn(msg)

          @attribute_methods_mutex = Mutex.new
        end

        # Use a mutex; we don't want two thread simaltaneously trying to define
        # attribute methods.
        @attribute_methods_mutex.synchronize do
          return if attribute_methods_generated?
          superclass.define_attribute_methods unless self == base_class
          super(column_names)
          column_names.each { |name| define_external_attribute_method(name) }
          @attribute_methods_generated = true
        end
      end