Re: [boost] Threads and mutexes : assign_to error

[Jacques Kerner]

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!

_______________________________________________
Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost