Ruby – Private module methods in Ruby


I have a two part question


  • I have an algorithm that performs some operation on a data structure using the public interface
  • It is currently a module with numerous static methods, all private except for the one public interface method.
  • There is one instance variable that needs to be shared among all the methods.

These are the options I can see, which is the best?:

  • Module with static ('module' in ruby) methods
  • Class with static methods
  • Mixin module for inclusion into the data structure
  • Refactor out the part of the algorithm that modifies that data structure (very small) and make that a mixin that calls the static methods of the algorithm module

Technical part

Is there any way to make a private Module method?

module Thing
  def; puts "Public method"; end
  def self.priv; puts "Private method"; end

The private in there doesn't seem to have any effect, I can still call Thing.priv without issue.

Best Solution

I think the best way (and mostly how existing libs are written) to do this is by creating a class within the module that deals with all the logic, and the module just provides a convenient method, e.g.

module GTranslate
  class Translator
    def perform( text ); translate( text ); end


    def translate( text )
      # do some private stuff here

  def self.translate( text )
    t =
    t.perform( text )