Simple Ruby module to add configurable, class/instance level logging to any class

loggable.rb

require 'logger'

# Adds configurable logger functionality to a class
#
#     class Foo
#       include Loggable
#
#       def complicated_method
#         logger.debug("Foo") { "Beginning long method" }
#         sleep(2)
#         logger.info("Foo") { "Long method finished" }
#       end
#     end
#
#     Foo.logger = Logger.new(STDOUT)
#     Foo.logger.level = Logger::INFO
#
#     Foo.new.complicated_method
#
#     #=> I, [2015-05-06T14:59:59.788163 #8176]  INFO -- Foo: Long method finished
module Loggable
  def self.included(base)
    base.extend ClassMethods
  end

  module ClassMethods
    attr_writer :logger

    def logger
      @logger ||= Logger.new(nil)
    end
  end

  def logger
    self.class.logger
  end
end