admin.rb

class Admin < Person
end

gistfile2.txt

Person.log_attributes --> ["foo"]
Admin.log_attributes --> nil

log.rb

module Log
    def self.included(base)
      base.extend(Log::ClassMethods)
    end

    module ClassMethods
      attr_accessor :log_attributes

      def watch_for_log(*args)
        @log_attributes ||= []
        @log_attributes += args.collect(&:to_s)
        puts self.log_attributes.inspect
      end

      def log_attributes
        (@log_attributes + (superclass.respond_to?(:log_attributes) ? superclass.log_attributes : [])).uniq
      end
    end
end

person.rb

class Person
  include Log
  watch_for_log :foo
end