How to convert void (__thiscall MyClass::* )(void *) to void (__cdecl *)(void *) pointer

Question

I want to build a \"IThread\" class which can hide the thread creation. Subclass implements the \"ThreadMain\" method and make it called automatically which seems like this:

Answer 1

You can't.

You should use a static function instead (not a static member function, but a free function).

// IThread.h
class IThread
{
public:
    void BeginThread();
    virtual void ThreadMain() = 0;
};

// IThread.cpp
extern "C"
{
    static void __cdecl IThreadBeginThreadHelper(void* userdata)
    {
        IThread* ithread = reinterpret_cast< IThread* >(userdata);
        ithread->ThreadMain();
    }
}
void IThread::BeginThread()
{
    m_ThreadHandle = _beginthread(
                     &IThreadBeginThreadHelper,
                     m_StackSize, reinterpret_cast< void* >(this));
}