gistfile1.cpp

Uint32 MESSAGE_EVENT = SDL_RegisterEvents(1);

/* In a thread dealing with network stuff */

while () {
    shared_ptr<Message> message = read_message_from_network();

    SDL_Event evt;
    evt.type = MESSAGE_EVENT;
    evt.user.data1 = // what?

    SDL_PushEvent(&evt);
}

/* In the event-handling thread */

while () {
    SDL_Event evt;
    SDL_PollEvent(evt);

    if (evt.type == MESSAGE_EVENT) {
        shared_ptr<Message> message = // what?
        handle_message(message);
    }
}