Re: [boost] [Boost][Thread] Non-copyable boost::thread

17 May 2010

      ----- Original Message ----- 
From: "Belcourt, Kenneth" <kbelco@sandia.gov>
To: <boost@lists.boost.org>
Sent: Monday, May 17, 2010 6:31 PM
Subject: Re: [boost] [Boost][Thread] Non-copyable boost::thread
...
On May 17, 2010, at 9:49 AM, vicente.botet wrote:
...
----- Original Message -----
From: "Belcourt, Kenneth" <kbelco@sandia.gov>
To: <boost@lists.boost.org>
Sent: Monday, May 17, 2010 5:41 PM
Subject: Re: [boost] [Boost][Thread] Non-copyable boost::thread
On May 17, 2010, at 2:25 AM, Anthony Williams wrote:
...
...
"Belcourt, Kenneth" <kbelco@sandia.gov> writes:
...
Intel-11.1 on Darwin is a recent compiler that will not compile  
this
code.
[ from libs/thread/test/test_thread_return_local.cpp ]
boost::thread make_thread_return_local(boost::thread::id* the_id)
{
  boost::thread t(do_nothing,the_id);
  return t;
}
The same error message is generated in both debug and release  
builds
on Darwin (though strangely it doesn't appear to be an error with
Intel 11.1 on Linux).
../libs/thread/test/test_thread_return_local.cpp(16): error #373:
"boost::thread::thread(boost::thread &)" (declared at line 111 of
"../
boost/thread/detail/thread.hpp") is inaccessible
    return t;
           ^
Any ideas how to work around this failure?
Explicitly move the return value:
return std::move(t);
or even
return std::thread(std::move(t));
Yup, that's what I figured.  But this compiler doesn't have  
std::move().
test_thread_return_local.cpp(17): error: namespace "std" has no  
member
"move"
   return std::move(t);
               ^
Any other ideas on how to get these Darwin / Intel tests running
Anthony?  Would the Boost.Move library currently under review work  
here?
If you are using Boost.Thread as I suspect, try
   return boost::move(t);
or even
   return boost::thread(boost::move(t));
Hi Vicente,
I'd considered this already but I'm not sure how to implement the move  
copy and assign constructors for Boost.Thread that Boost.Move requires.
Here's the changes I've made, just missing the implementations for  
move copy and assign.
[ boost/thread/detail/thread.hpp ]
private:
       BOOST_MOVABLE_BUT_NOT_COPYABLE(thread)
public:
        // move ctor
        thread(BOOST_RV_REF(thread) x);
// move assign
        thread& operator=(BOOST_RV_REF(thread) x);
private:
        // thread(thread&);
        // thread& operator=(thread&);
Since Boost.Thread has it's own partial move implementation in  
boost::detail::thread_move, it seems that some work is necessary to  
integrate (or re-implement) thread_move in terms of boost::move.   
That's why I thought I'd ping Anthony and see if this is even worth  
considering.
As you said Boost.Thread implements in his way its own move semantics. It defines already an overload for 
  boost::move(thread&)

You don't need to integrate Boost.Thread and Boost.Move as far as you don't wanted to use the Boost.Container library, that is is not reviewed yet. I guess Anthony, the author of Boost.Thread will replace its implementation by one using Boost.Move once Boost.Move will be released (if accepted of course ;).

I see that the Boost.Thread documentation don't includes any reference to the provided boost::move. Anthony, have you removed it?

Best,
Vicente