Question

I am trying to declare a static class within a parent class and initialize it, but I seem to be getting all sorts of errors.

/* MainWindow.h */
    class MainWindow
    {
        private:
        static DWORD WINAPI threadproc(void* param);
        static MainWindow *hWin;
    };
/* MainWindow.cpp */
#include "MainWindow.h"
      void MainWindow::on_pushButton_clicked()
        {
            HANDLE hThread = CreateThread(NULL, NULL, threadproc, (void*) this, NULL, NULL);
            WaitForSingleObject(hThread, INFINITE);
            CloseHandle(hThread);
        }

        DWORD WINAPI MainWindow::threadproc(void* param)
        {
            hWin = (MainWindow*) param;
            //Be able to access stuff like hWin->run();
            return 0;
        }

I have tried using MainWindow::hWin = (MainWindow*) param; and MainWindow::hWin = new MainWindow((MainWindow*) param)); and many others, but none seem to work. What is the proper way to do this? Are there any resources anybody would recommend on this subject, I have been tangling with class problems for a few days now and am very frustrated.

Answer 1

Static members always consist of a declaration and a definition, you lack the definition in your cpp file. Put the following line outside of any functions:

MainWindow* MainWindow::hWin;

You can read more here or here.