Private module methods in Ruby

Question

I have a two part question

Best-Practice

• 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 self.pub; puts "Public method"; end   private   def self.priv; puts "Private method"; end end 

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

Answer 1

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      private      def translate(text)       # do some private stuff here     end   end    def self.translate(text)     t = Translator.new     t.perform(text)   end end