Boost C++ Libraries

Given wait_all_until_error_source(), it might be more reasonable to make a wait_all_...() that collects all errors instead of presenting only the first:

template< typename Fn, typename ... Fns >
std::vector< typename std::result_of< Fn() >::type >
wait_all_collect_errors( Fn && function, Fns && ... functions) {
    std::size_t count( 1 + sizeof ... ( functions) );
    typedef typename std::result_of< Fn() >::type return_t;
    typedef typename boost::fibers::future< return_t > future_t;
    typedef std::vector< return_t > vector_t;
    vector_t results;
    results.reserve( count);
    exception_list exceptions("wait_all_collect_errors() exceptions");

    // get channel
    std::shared_ptr<
        boost::fibers::buffered_channel< future_t > > chan(
            wait_all_until_error_source( std::forward< Fn >( function),
                                         std::forward< Fns >( functions) ... ) );
    // fill results and/or exceptions vectors
    future_t future;
    while ( boost::fibers::channel_op_status::success == chan->pop( future) ) {
        std::exception_ptr exp = future.get_exception_ptr();
        if ( ! exp) {
            results.push_back( future.get() );
        } else {
            exceptions.add( exp);
        }
    }
    // if there were any exceptions, throw
    if ( exceptions.size() ) {
        throw exceptions;
    }
    // no exceptions: return vector to caller
    return results;
}

The implementation is a simple variation on wait_first_success(), using the same exception_list exception class.