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

Subject: Re: [boost] [Thread] Non-copyable boost::thread
From: vicente.botet (vicente.botet_at_[hidden])
Date: 2010-05-17 16:06:46

----- Original Message ----- 
From: "Belcourt, Kenneth" <kbelco_at_[hidden]>
To: <boost_at_[hidden]>
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_at_[hidden]>
>> To: <boost_at_[hidden]>
>> 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_at_[hidden]> 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