require_implementation.rb

module RequireImplementation
  def require_implementation(method_name)
    define_method method_name do
      raise NotImplementedError, "#{self.class.name} must implement #{method_name}"
    end
  end
end


class TestClass
  extend RequireImplementation
  require_implementation :foo
end

class BrokenSubclass < TestClass
end

class WorkingSubclass < TestClass
  def foo
    puts "Fooey"
  end
end


begin
  BrokenSubclass.new.foo
rescue Exception => ex
  puts ex.message
end

WorkingSubclass.new.foo