Call AfxBeginThread with class member function?

Question

How can I call AfxBeginThread with an arbitrary non-static class method? Maybe there is something I can do with boost bind? Below is the expected usage from Microsoft (and is an example of calling a non-static method but it is hard-coded which method):

UINT MyThreadProc( LPVOID pParam )
{
    CMyObject* pObject = (CMyObject*)pParam;

    if (pObject == NULL ||
        !pObject->IsKindOf(RUNTIME_CLASS(CMyObject)))
    return 1;   // if pObject is not valid

    // do something with 'pObject'

    return 0;   // thread completed successfully
}

// inside a different function in the program
...
pNewObject = new CMyObject;
AfxBeginThread(MyThreadProc, pNewObject);

Solution 1

You will need a static function to pass to AfxBeginThread, but it can be a very simple function that calls into the object. Here's an untested template function that might work.

template<class T>
UINT __cdecl StartThread(LPVOID pParam)
{
    return ((T*)pParam)->MyThreadProc();
}

Solution 2

Your code sample is fine. You will need a thread function for each different non-static class method you want to call in separate threads.

boost:bind will not help you whatsoever... AfxBeginThread would have to be a C++ template function, otherwise it cant be compatible with boost::bind or C++11 lambdas with captures.

One Alternative is to create a struct, with an enum for each class/method combination you will have, but this still requires you to manually add code to both the enum and the callback function for each class/method combination. However its not that much less code than creating a separate thread function for each class/method combination.

struct ThreadData
{
  LPVOID object;
  enum ObjectCallType {
    Foo_Foo,
    Foo_Bar
  } objectCallType;
  LPVOID* param;
  ThreadData( LPVOID pobject, ObjectCallType poct, LPVOID* pparam=0 )
  :object(pobject), objectCallType(poct), param(pparam) {}
};

UINT MyThreadProc( LPVOID pParam )
{
    TheadData* thData = (ThreadData*)pParam;
    try 
    {
        switch( thData->objectCallType )
        {
            case ThreadData::Foo_Foo:
                Foo* foo = (Foo*)thData->object;
                foo->foo();
                break;
            case ThreadData::Foo_Bar:
                Foo* foo = (Foo*)thData->object;
                foo->bar( thData->param );
                break;
            default:
                throw std::exception("unhandled method call type");
        }
    }
    catch( std::exception& e )
    {
        std::cerr << e.what() << std::endl;
        delete thData;
        return 1;
    }
    delete thData;
    return 0;
}



//usage:
AfxBeginThread(MyThreadProc, new ThreadData(myFooObject,ThreadData::Foo_Bar,myFooCallParam));

Boost example (untested):

boost::thread myFooFooThread( boost::bind( &Foo::Foo, myFooObject ) );