Inheriting class methods from modules / mixins in Ruby

Question

It is known that in Ruby, class methods get inherited:

class P
  def self.mm; puts \'abc\' end
end
class Q < P; end
Q.mm # works

However

Answer 1

As Sergio mentioned in comments, for guys who are already in Rails (or don’t mind depending on Active Support), Concern is helpful here:

require 'active_support/concern'

module Common
  extend ActiveSupport::Concern

  def instance_method
    puts "instance method here"
  end

  class_methods do
    def class_method
      puts "class method here"
    end
  end
end

class A
  include Common
end