Re: [Boost-users] Using unique_future in C++03, boost 1.47.0

Subject: Re: [Boost-users] Using unique_future in C++03, boost 1.47.0
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2011-12-13 18:16:15

Le 02/12/11 07:27, Kelvin Chung a écrit :
> I have a bunch of boost::packaged_task<unsigned long>, which I intend 
> to execute on separate boost::threads.  Before I do that, though, I 
> want to insert each boost::unique_future<unsigned long> in a container 
> as I make them.  Given that I am using C++03 and boost 1.47.0 (boost 
> 1.48.0 craps out over an ambiguous overload of boost::move), I have 
> something like the following:
>
> std::deque<boost::unique_future<unsigned long>> futures;
> // std::deque<boost::thread> evalThreads;    TODO
> for (…) {
>     boost::packaged_task<unsigned long> task = …;    // Create the 
> tasks, one at a time
>     boost::unique_future<unsigned long> taskResult = task.get_future();
>     // boost::thread taskThread(boost::move(task));    TODO
>
>     // boost::unique_future and boost::thread can't be copied, but can 
> be moved
>     futures.push_back(boost::move(taskResult));
>     // evalThreads.push_back(boost::move(taskThread));    TODO
> }
> boost::wait_for_all(futures.begin(), futures.end());
> // Now we can do stuff with futures
>
> The problem is that the code above is failing to compile, saying that
>
> /usr/include/c++/4.1.2/ext/new_allocator.h:104: error: passing ‘const 
> boost::unique_future<long unsigned int>’ as ‘this’ argument of 
> ‘boost::unique_future<R>::operator 
> boost::detail::thread_move_t<boost::unique_future<R> >() [with R = 
> long unsigned int]’ discards qualifiers
>
> I don't fully understand the problem, but I blame the move emulation.  
> How do I fix this?
>
Globally the move emulation on Boost.Thread is quite broken. There is a 
plan to adapt it to Boost.Move which we hope will solve most of the 
current issues.

I have tried to fix this with the current design I don't reach to find a 
solution. I suspect that we will need to wait until the adaptation is 
done if no one finds a trike solution.

Best,
Vicente