Ruby Module/Class Interdependency playground

concerning-modules.rb

#!/usr/bin/env ruby
# © 2025 Konstantin Gredeskoul, All rights reserved.
#
# This script is a proof of concept to show how to use ActiveSupport::Concern 
# to manage dependencies between modules and classes. The main idea is to use 
# the included block to include the dependencies of a module, and the 
# class_methods block to define class methods.
# 
# Ultimately, the script prints all of the the methods of the Host, Bar, and 
# Foo classes and modules to show the result of the concern implementation.
#
# Run simply as `ruby 

require "active_support/concern"

module Foo
  extend ActiveSupport::Concern

  included do |base|
    def hello
      puts "hello"
    end

    def goodbye
      puts "goodbye"
    end 
  end


  class_methods do
    def included(another)
      def ciao
        puts "ciao! From #{another}"
      end 
    end

    def class_help
      puts "class_help"
    end
  end
end

module Bar
  include(Foo)

  extend ActiveSupport::Concern

  included do |base|
    base.include(Foo)
  end
end

class Host
  include Bar # It works, now Bar takes care of its dependencies
end

require 'pp'

# ———————————————————————————--------------------------------

def line; puts '—' * 40; end

def standard_methods
  @standard_methods ||= [ 
    BasicObject.methods + 
    Object.methods + 
    Object.new.methods + 
    Module.methods + 
    Module.new.methods + 
    Kernel.methods + 
    ::PP::ObjectMixin.methods  +
    PrettyPrint.methods
  ].sort.uniq
end

def ruby_functions(methods: [])
  methods - standard_methods
end

puts "\nCLASS/MODULE METHODS\n"

print "Host:  "
pp  ruby_functions(methods: Host.methods)

print "Bar:   " 
pp  ruby_functions(methods: Bar.methods)

print "Foo:   " 
pp  ruby_functions(methods: Foo.methods)

line

puts "\nINSTANCE METHODS\n"
print "Host:  "
pp  ruby_functions(methods: Host.new.methods)

pp Host.ancestors