oneof field: define an empty member

[Maxim]

Hi all,

I am looking for some guidance what would be the best way to define a member of a oneof field where the actual value of the member does not matter and it is sufficient to know that it was selected.

A somewhat contrived example:

message SearchRequest {
    oneof options {
        ValueDoesNotMatter search_all = 1;
        ValueDoesNotMatter search_starred = 2;
        string search_named = 3;
    }
}

My first choice would be an empty message like google.protobuf.Empty, but it seems that in C++ it is somewhat cumbersome to select that member:

message.mutable_options().set_allocated_search_all(new google::protobuf::Empty);

I thought maybe I am doing it wrong and there is a better way?

Thanks,

Maxim