複数のモジュールにあるStaticeMethodsを1つのクラスのクラスメソッドにまとめる

myconcern.rb

module Concern 
  def self.extended(base)
    base.instance_variable_set("@dependencies", [])
  end
  def append_features(base)
   if base.instance_variable_defined?("@dependencies")
     base.instance_variable_get("@dependencies") << self
   else
     super
     @dependencies.each {|dep| base.send(:include, dep)}
     base.extend const_get("ClassMethods") if const_defined?("ClassMethods")
   end
  end
end
module M
  extend Concern
  module ClassMethods
    def m1
      puts "hello"
    end
  end
end
module M2
  extend Concern
  include M
  module ClassMethods
    def m2
      m1
    end
  end 
end
class C
  include M2
end
C.m2#=> hello