Re: [boost] Re: future of boost.threads

From: Stefan Seefeld (seefeld_at_[hidden])
Date: 2004-02-08 19:55:13

Jeff Garland wrote:

>>It can always be added on a higher level that wraps the 'join()' call.
> 
> 
> This might be true, but I would think the exception abstractions and framework
> would need to be part of the library.  If you look at the RW docs you there
> are some examples that show they build it in at this level.  It looks
> something like:
>   
>   ThreadFunction someThread = ...;
>   try {
>     someThread.start(); // Start the thread
>     someThread.join();  
>     someThread.raise(); // Rethrow any exception that was caught!
>   }
>   catch(rethrowable_exception& msg) {
>     cout << "Exception! " << msg.why() << endl;
>   }

for this to work you'd need a way to marshall exceptions from one thread
to another, which imposes some constraints on the exception types to be thrown.

A similar problem arises when C++ code is used to wrap a C 'middleware' library,
where you want to pass through exceptions from C++ callbacks to the C++ application.
I'v seen examples where the C++ wrapper code defines its own exception types
that provide 'clone()' methods so they could be stored and rethrown in a different
context. I'm curious to learn whether the boost experts have better techniques
to deal with these situations.

Regards,
                Stefan