Diaries of Learning Qt (1.1) Capture the Close Event

We want to  ask  the user whether he'd like to save the change when he tries to close the window, so we need to capture the close event.
In fact, when the user clickes the X button on the title bar, close events will be sent to the widget and be recieved by this handler:  

      void QWidget::closeEvent(QCloseEvent * event)

By defult, it will accept the event and close the widget directly, so generally, when we wants to capture the close event, we reimple the closeEvent function like this:

    class MainWindow : public QMainWindow
    {
        Q_OBJECT
    public:
        MainWindow();
    protected:
        void closeEvent(QCloseEvent *event);
......
    void MainWindow::closeEvent(QCloseEvent *event)
    {
         if (maybeSave()) {
             writeSettings();
             event->accept();
         } else {
             event->ignore();
         }
     }

In this scrap, maybeSave() is a function asking the user to save. It will return true if he wants to and false if not.
So by reimpling the closeEvent() function, we can ask before closing.