After some twitter discussion we evaluate our different module strategies

modules_modules.rb

# Scope of the debate:
# - not managing state, use class for that
# - not using namescoped classes for faux provacy, plain class is prefereable for that
# - alternative to typical module such as:
module M
  def self.included(base)
    base.extend ClassMethods
    base.class_eval do
      scope :disabled, -> { where(disabled: true) }
    end
  end

  module ClassMethods
    ...
  end
end

## When used for including (in Rails):
module SomeResponsabilityConcern
  extend AvtiveSupport::Concern

  included do
    has_many :foos
    belongs_to :bar
  end

  class_methods do
    #...
  end
  
  def instance_method_one
  end
end
# Pros:
# - easy
# - syntax sugar (included do...end instead of module ClassMethods + extend)
# Cons:
# - it adds behaviour into the controller (not very SRP)
# - it hides ruby you might not know well enough hiding its side effects

## When not including:

module TematicFunctions
  def public_method
    # other_meth can't be called
  end
  module_function :public_method
  private
  def other_meth
  end
end
# Pros:
# - just ruby
# - recommended by ruby-code-style-guide / ruboto
# Cons:
# - only public module level functions are easy to use

module SegregatedLogic
  extend self # public function available at module level
  def pub_goer
    puts "#{investigator} is the best"
  end
  private
  def investigator
    print 'Magnum'
  end
end
# Pros:
# - just ruby
# - public functions access private auxiliars
# - recommended by practicing-ruby https://practicingruby.com/articles/uses-for-modules-4
# Cons:
# - "extend self" non obvious for learners
# Example: 
# SegregatedLogic.pub_goer
# => Magnum is the best