Question

This is inside a Menu class. The problem is addAction. This works, but there is no connection to slot:

QMenu* menu2 = new QMenu("Test");
menu2->addAction("Test");

When I do this:

QMenu* menu2 = new QMenu("Test");
menu2->addAction("Test", Menu, test);

I get compiler error: “error: expected primary-expression before ‘,’ token”

I mean to call the test() function in the Menu class. What am I doing wrong?

Answer 1

Well, the error comes from passing Menu as an argument. You say Menu is a class, and classes are not expressions on themselves.

If you need to call test on an instance of Menu, where Menu is not a derivate from QObject (ie. no slots available), then you can just create a slot in the widget that contains the QMenu itself (probably a QMainWindow), and implement the call in there!

Edit: to add an example.

class MainWindow : public QMainWindow {
  Q_OBJECT
 // Usual declarations...

private slots:
  void myCustomSlot();
};

Now, say that you’re populating the main window inside its constructor:

MainWindow::MainWindow(...) {
   // Some initialization code

   QMenu *menu2 = new QMenu("Test");
   menu2->addAction("Test", this, SLOT(myCustomSlot));
   // Some more initialization code
}

// ...

void MainWindow::myCustomSlot() {
   instanceOfMenu->test();
}

Of course, if you’re creating the menu outside that class, you’d need to make the slot public, but that’s another issue