Ruby Module with Class and Instance methods extended

ruby_module_with_class_instance.rb

module Persistence
  def self.included(klass)
    klass.extend(ClassMethods)
  end

  module ClassMethods
    def all
      puts 'all'
    end

    def find(id)
      puts "looking for entity with id=#{id}"
    end
  end

  def save
    puts 'saving'
  end

  def update
    puts 'updating entity'
  end
end

class User
  include Persistence
end

u = User.new

# instance methods
u.save #=> saving
u.update #=> updating entity

# class methods
User.all #=> all
User.find(1) #=> looking for entity with id=1