Question

I am reading a blog post on the code quality of the Doom 3 source code, and I’ve gotten stuck on a piece of C++ code I can not make sense of. I should say that I am not a C++ programmer.

The offending code looks as follows:

Sys_StartAsyncThread(){                          // The next look runs is a separate thread.
    while ( 1 ){
        usleep( 16666 );                         // Run at 60Hz
        common->Async();                         // Do the job
        Sys_TriggerEvent( TRIGGER_EVENT_ONE );   // Unlock other thread waiting for inputs
        pthread_testcancel();                    // Check if we have been cancelled by the main thread (on shutdown).
    }
}

(taken from http://fabiensanglard.net/doom3/index.php, under the topic “Unrolling the loop”)

This looks to me as a closure being passed as a parameter to the return value of Sys_StartAsyncThread() – but to my knowledge this is not possible in C++, and also Sys_StartAsyncThread() is of void type, so what’s going on here?

The definition of Sys_StartAsyncThread() can be found here.

Answer 1

It looks like a typo. According to here, there should be a semicolon after Sys_StartAsyncThread();.