variables in a static function
Author
Okay, so I've been using this little Windows wrapper for my games for a while now, it does everything I need. But now I'm trying to extend it, and I'm running into problems.
All my callback functions are static (which I assume is the way it's supposed to be). But the problem is that in my main message processor, I'm trying to call a dialog box. For this I need the handle to the current instance (hInst).
Problem is, my current instance isn't static and thus I can't access it. If I add the "static" keyword to it, MSVC throws me a bunch of "unresolved external symbol" errors.
How do I fix this? (and why is coding for Windows using classes such a pain?)
Callback functions often have a DWORD or LPVOID parameter associated with them. In these cases, I usually pass a pointer to the object (this) to the callback function. Like with CreateThread, I have two functions, one that is static, and is of the DWORD WINAPI ThreadProc_Static(LPVOID lpParameter) form, and the other that is a member function of the form DWORD ThreadProc() form. In the static function, I simply cast the lpParameter argument to the appropriate class pointer type, and call the member ThreadProc() function. So I basically get a callback function that ends up being a member function.
class CClass{ public: CClass() : mhStop(false), mhThread(NULL) { mhThread = CreateThread(NULL, 0, CClass::ThreadProc_Static, (LPVOID)this, 0, NULL); } ~CClass() { mStop = true; if (WaitForSingleObject(mhThread, 1000) == WAIT_TIMEOUT) TerminateThread(mhThread, -1); CloseHandle(mhThread); } private: HANDLE mhThread; bool mhStop; static DWORD WINAPI ThreadProc_Static(LPVOID lpParameter) { return reinterpret_cast<CClass*>(lpParamter)->ThreadProc(); } DWORD ThreadProc() { while (!mhStop) { Sleep(100); } return 0; }};
Author
Thanks O_o, your solution worked.
Agony, yours looks a lot more flexible though, I'll be sure to keep it around for future reference. One question though, I thought callback functions were supposed to have four parameters? (HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)?
Thanks for the help guys!
Agony, yours looks a lot more flexible though, I'll be sure to keep it around for future reference. One question though, I thought callback functions were supposed to have four parameters? (HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)?
Thanks for the help guys!
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