Re: [boost] Boost.Threads, N2178, N2184, et al

From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2007-03-21 18:01:27

> *  The N2184::thread is non-copyable like boost::thread, but movable
> (taking advantage of new C++ language and std::lib features).  Movable
> N2184::thread maintains the one-to-one mapping between the std::thread
> and the OS thread which boost has (sole ownership semantics).  It just
> adds the ability to move the thread between scopes (such as return
> from factory functions).  I recently drew the analogy this way:
>
> boost::thread is like a scoped_ptr to the OS thread.
> N2184::thread is like an auto_ptr to the OS thread (the proposed
> unique_ptr would be a more accurate analogy).

This assumes that it is not desirable for the same N2184::thread object to 
be shared between multiple owners. The rationale given for the non-copyable 
semantics of boost::thread states that the only time you need copyable 
handle is in what they call "Use case 6: Creation of a thread whose 
ownership is shared between multiple objects", which is like saying that you 
only need shared handles when you need shared handles 
(http://www.boost.org/doc/html/threads/rationale.html#threads.rationale.non-copyable.shared.)

I suppose similar argument can be made for movable semantics for 
N2184::thread, but again, what about this use case? Does N2184 argue that 
this use case does not exist in practice?

Emil Dotchevski