Question

This:

typedef HRESULT (*PFN_HANDLE)(ClassName&);

It’s used like this:

DWORD ClassName::Wait(PFN_HANDLE pfnh_foo)
{
  while (!done) {
    waitCode = WaitForMultipleObjects(paramA, paramB, paramC, paramD)

    if (waitCode == WAIT_OBJECT_0)
    {
      pfnh_foo(*this);
    }
    else
      done;
  }
  return waitCode;
}

It appears that Wait does nothing except block when it gets to WaitForMultipleObjects and then after that does this strange pfnh_foo thing and either loops back around to wait again or exits

Answer 1

Your wait() function basically waits for multiple objects and then invoke function using function pointer PFN_HANDLE if the wait is successful ( indicated by return value WAIT_OBJECT_0).

pfnh_foo(*this);

This calls the function pointed by pfnh_foo with argument *this.

Lets say we have function:

HRESULT someFunction(ClassName& myClassInstance)
{
//blah .. blah
}

Wait will be invoked like this:

PFN_HANDLE pfnh_foo = &someFunction;  //function pointer to someFunction
wait(pfnh_foo);