Function matching in Qt

Question

Hello, I have some trouble with Qt.

I have a class 'Core'

class Core {

   public:

        static QString get_file_content(QString filename);
        static void setMainwindow(Ui::MainWindow const *w);

   private:
        static MainWindow *main_window;
};

and class 'MainWindow' in namespace Ui:

namespace Ui {
    class MainWindow;
}

class MainWindow : public QMainWindow {
    Q_OBJECT
public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
};

In MainWindow constructor I make

 MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    Core::setMainwindow(this);
}

and gets error

mainwindow.cpp:8: error: no matching function for call to 'Core::setMainwindow(MainWindow* const)'

Of cource, i include core.h with declaration of 'Core' class.

That's occurs only on setMainwindow method.

So the questions is - why Core class method setMainwindow() is invisible in MainWindow class?

Answer 1

Hey,

Did you add "Core.h" in your MainWindow's cpp/h file ?

Did you try without parameter in setMainWindow, just to check if it's not something related to it ?

Edit : Yeah seems to me you need MainWindow as parameter, not Ui::MainWindow, don't you think ?

Answer 2

The problem is that your Core::setMainwindow method takes a Ui::MainWindow* and you are passing a MainWindow*. From the code you posted you have two MainWindow classes, one in the namespace Ui and one in the top-level namespace. Is this what you mean or should there only be the one in Ui perhaps?

Answer 3

Your MainWindow class isn't nested inside the Ui namespace. You forward-declared the Ui::MainWindow class, but then implemented a separate ::MainWindow class (in the global namespace). Because of this, your Core::setMainwindow takes a Ui::MainWindow but you're passing a ::MainWindow.

I'm guessing that this lack of nesting is correct -- and Ui::MainWindow is generated by Qt Designer, and MainWindow is the implementation class that contains all of your custom code. If so, change your code to:

class Core {

   public:

        static QString get_file_content(QString filename);
        static void setMainwindow(MainWindow const *w);

   private:
        static MainWindow *main_window;
};