Douglas Gregor wrote:

> On Wednesday 30 April 2003 08:44 am, Jacques Kerner wrote:
>   
> 
> >Hi,
> >
> >I get the following error :
> >
> >error C2664: 'void boost::function0<R,Allocator>::assign_to(Functor)' :
> >unable to convert parameter 1 from 'const CTaskManager' to 'CTaskManager'
> >
> >when doing this :
> >
> >class CTaskManager
> >{
> >    public:
> >        CTaskManager();
> >        ~CTaskManager();
> >        void operator()() {}
> >
> >    private:
> >        boost::mutex m_mutex;
> >}
> >
> >and
> >
> >CTaskManager taskManager;
> >boost::thread_group mainThreadGroup;
> >mainThreadGroup.create_thread(taskManager);
> >mainThreadGroup.join_all();
> >
> >The error dissapears when I remove the mutex from the definition of
> >CTaskManager ... (?!!)
> >
> >So what is the right way to use mutex and threads together? Do I have to
> >declare the mutex outside of the
> >functor? Why?
> >    
> >
> 
> Mutexes are not copyable, and when you pass taskManager to create_thread it 
> tries to make a local copy of the function object . If you would prefer to 
> pass a reference to taskManager to create_thread, do this:
> 
>   mainThreadGroup.create_thread(boost::ref(taskManager));
> 
> 	Doug
> 
> _______________________________________________
> Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
> 
>   
> 
Thank you very much, it works great. I had missed the fact that 
create_thread makes a copy
of the functor. Thanks again!


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