"Peter Dimov" <pdimov@mmltd.net> writes:
It seems to me that most thread participants (pun not intended) are missing the point. You can execute a function object in a thread. That function object can, in the general case, return a value. When you join() that thread, you should be able to retrieve the return value of the function object. (Here's your call graph.)
Now, in C++ functions actually can return either a value or an exception. That is,
int f();
can return an int or throw an exception. Hence, when you execute that f in a thread, you should be able later to call
int thread::join();
and it should return whatever f returned. Obviously, if f has thrown an exception, there is no int to return, so join() should throw an exception, too. What kind of exception should join() throw? It would make sense to replicate the original, wouldn't it?
Note that you can't add exception marshalling on a higher level (with the current interface) because you can't access a thread's state (to retrieve its return value or exception) from another thread.
Makes sense to me. I guess I just wanted to know if it was as simple as that. -- Dave Abrahams Boost Consulting www.boost-consulting.com