Modules

gistfile1.rb

module MyModule
  def self.included(base)
    puts base
    base.instance_variable_set :@my_instance_variable, {}
    base.extend ClassMethods
  end

  module ClassMethods
    def my_instance_variable
      # self is ClassA here, so we need to call superclass
      superclass.instance_variable_get :@my_instance_variable # => {}
    end
  end
end

class MySuperClass
  include MyModule
end

class ClassA < MySuperClass; end
puts ClassA.my_instance_variable

module Z
extend self

def hello
puts "HI"
end
end