class Class
  def const_missing(id)
    puts "Class#const_missing"
  end
end

module Mdl
  def const_missing(id)
    puts "Mdl#const_missing"
  end
end

class Cls1
  include Mdl
  def const_missing(id)
    puts "Cls1#const_missing"
  end
end

class Cls2 < Cls1
  def hoge
    puts "CONST_VAR: #{CONST_VAR}"
  end
  def const_missing(id)
    puts "Cls2#const_missing"
  end
end

# Class で定義した cons_missing が実行される
Cls2.new.hoge # :=> Class#const_missing