Re: [Boost-users] [Thread] Constructing a move-only object asyncronously

Le 20/03/13 18:56, Alexander Lamaison a écrit :

"Vicente J. Botet Escriba" writes:

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Le 20/03/13 13:26, Vicente J. Botet Escriba a écrit :

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Le 20/03/13 00:22, Alexander Lamaison a écrit :

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"Vicente J. Botet Escriba" writes:

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Le 19/03/13 20:30, Alexander Lamaison a écrit :

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"Vicente J. Botet Escriba" writes:

> Le 19/03/13 19:40, Alexander Lamaison a écrit : >> I'm trying to create a move-only object asyncronously using >> Boost.Thread >> unique_future but I'm running into trouble: >> >> error C2248: 'A::A' : cannot access private member declared in >> class 'A' >> c:\users\awl03\documents\visual studio >> 2005\projects\boost_1_51_0\boost\thread\future.hpp 493 >> >> I've tried all sorts of ways to work around this but always end >> up with >> some variation or other of this error message. What am I doing >> wrong? >> snip

> you need to use version 4 to got this functionality. I assume this requires Boost 1.53?

> I have modified your example to use boost::future (*) and use > packaged_task with a signature parameter (**). With this change it to > works for the following toolsets. Thanks! Can you give me an idea of what changed in v4 to enable this? I've looked through the history but nothing stands out.

I tried to make it work using just class thread rather than anything in , but I couldn't work out how for a non-default constructible class.

I have just tried your example defining

#define BOOST_THREAD_USES_MOVE

and it works also. Perfect. Thanks :)

I'm assuming this solves the problem because the previous thread-internal move emulation didn't realise class A was movable and so tried to copy it. Is that right?

Yes, your code declared a move only class using the Boost.Move emulation. Boost.Thread has defined equivalent macros that use both emulations. Could you try with the following without defining BOOST_THREAD_USES_MOVE

//#define BOOST_THREAD_USES_MOVE

class A : public noncopyable { BOOST_THREAD_MOVABLE_ONLY(A)

public: A(int ) {}

A(BOOST_THREAD_RV_REF(A) ) {}

A& operator=(BOOST_THREAD_RV_REF(A) ) { return *this;}

};

Ah, you will need to add

BOOST_THREAD_DCL_MOVABLE_BEG(T) A BOOST_THREAD_DCL_MOVABLE_END

so that there is no conflict with Boost.Move. This second version is working for me without those two defines. No conflicts occuring.

Great, glad so see that you have a solution now. Vicente