QObject connection "Cannot convert argument 3 from 'Class that in Inherits QObject' to QObject*

Question

I'm using the MVC pattern and I'm trying to connect a signal from my view class with my controller class that inherits QObject

class View : public QWidget
{
    Q_OBJECT

private:

   Controller* controller;

   QPushButton* startButton;

   void addControls(QVBoxLayout* mainLayout);

public:
   explicit View(QWidget *parent = nullptr);

   void setController(Controller* c);
};

#endif // VIEW_H

This are the methods

void View::addControls(QVBoxLayout *mainLayout)
{
    //I'm adding the button
}

View::View(QWidget *parent) : QWidget(parent)
{
//Layout
}

void View::setController(Controller *c){
    controller = c;

    connect(startButton, SIGNAL(clicked()), controller, SLOT(begin()));
//ERROR controller is a Controller* and it can't be converted it to const QObject*
}

And this is the Controller class

class Controller : public QObject
{
    Q_OBJECT
private:
    QTimer* timer;

    View* view;
    Model* model;

public:
    explicit Controller(QObject *parent = nullptr);
    ~Controller();

    void setModel(Model* m);
    void setView(View* v);

public slots:
    void begin() const;

};

#endif // CONTROLLER_H

And the methods

Controller::Controller(QObject *parent):
    QObject(parent), timer(new QTimer)
{
    connect(timer, SIGNAL(timeout()), this, SLOT(next()));
}

Controller::~Controller() { delete timer; }

void Controller::setModel(Model* m) { model = m; }

void Controller::setView(View* v) { view = v; }

void Controller::begin() const {
    timer->start(200);

}

For good measure, here is the main where I set each component

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    View w;
    Controller c;
    Model m;

    c.setModel(&m);
    c.setView(&w);
    w.setController(&c);
    w.show();
    return a.exec();
}

I've tried everything I could think of, can't make it work..

Answer 1

Stop using the terrible text-based slot connection interface. Use the modern one that gives nice compile errors:

 QObject::connect(startButton, &QPushButton::clicked, controller, &Controller::begin);