Log deprecated methods in Rails app

deprecate.rb

DEPRECATE_LOGGER = Logger.new(Rails.root.join("log", "deprecate.log").to_s).tap do |logger|
  logger.formatter = proc { |s, time, p, msg| "[#{time}] #{msg}\n" }
end

class Module
  def __deprecate(meth)
    aliased, punc = meth.to_s.sub(/([?!=])$/, ""), $1
    module_eval <<-RUBY, __FILE__, __LINE__ + 1
      def #{aliased}_with_deprecated#{punc}(*args, &block)
        DEPRECATE_LOGGER.debug { "\#{self.class.name}##{meth} was called from \#{caller(1, 1).first}." }
        __send__(:#{aliased}_without_deprecated#{punc}, *args, &block)
      end
      alias_method_chain :#{meth}, :deprecated
    RUBY
  end

  def __deprecate_accessor(meth)
    __deprecate(meth)
    __deprecate("#{meth}=")
  end

  def __deprecate_reader(meth)
    __deprecate(meth)
  end

  def __deprecate_writer(meth)
    __deprecate("#{meth}=")
  end
end

USAGE

__deprecate def old_method(a, b, &bkock)
  :
end

attr_accessor :old_accessor
__deprecate_accessor :old_accessor

attr_reader :old_reader
__deprecate_reader :old_reader

attr_writer :old_writer
__deprecate_writer :old_writer