module M

  def base_constant(constant)
    self.class.const_get(constant)
  end

  def display_constant
    puts "Module M needs to access the #{base_constant(:SOME_CONSTANT)}"
  end

end

class A
  SOME_CONSTANT = "Constant from A"
  include M
end

class B
  SOME_CONSTANT = "Constant from B"
  include M
end

a = A.new
a.display_constant

b = B.new
b.display_constant