with_enumerated.rb

def with_enumerated(subject, method_name)
  begin
    subject.define_singleton_method("#{method_name}_with_enum") do |*args, &block|
      return enum_for(method_name, *args) unless block.present?
      public_send("#{method_name}_without_enum",*args, &block)
    end
    subject.singleton_class.alias_method "#{method_name}_without_enum", method_name
    subject.singleton_class.alias_method method_name, "#{method_name}_with_enum"
    yield
  ensure
    subject.singleton_class.alias_method method_name, "#{method_name}_without_enum"
    subject.singleton_class.remove_method "#{method_name}_with_enum"
    subject.singleton_class.remove_method "#{method_name}_without_enum"
  end
end