Qt5 Connect Custom WindowClose Signal To A Different Window

Question

I'm trying to connect a signal from one class to a slot in another class but when I do, my application crashes on startup. I read some other posts on here and the Qt forums that eluded to connecting custom signals as such but I think I'm connecting them wrong. Any help is greatly appreciated.

AdministrativeWindow.h

class AdministrativeWindow : public QMainWindow
{
    Q_OBJECT

    public:
        explicit AdministrativeWindow(QWidget *parent = 0);
        ~AdministrativeWindow();

    private slots:
        void on_actionExit_Administrative_Window_triggered();

    private:
        Ui::AdministrativeWindow *ui;

    signals:
        void windowClose();
};

AdministrativeWindow.cpp

void AdministrativeWindow::on_actionExit_Administrative_Window_triggered()
{
    emit windowClose();
    close();
}

MainWindow.cpp

connect(adminWindow, SIGNAL(windowClose()), this, SLOT(adminWindowClose()));

void MainWindow::on_ConfigureUsersBtn_clicked()
{
    if(adminWindow == NULL)
    {
        adminWindow = new AdministrativeWindow();
        adminWindow->show();
    }
    else if(adminWindow->isVisible())
    {
        adminWindow->activateWindow();
        adminWindow->showNormal();
    }
    else
    {
        adminWindow->show();
    }
}

void MainWindow::on_adminWindowClose()
{
    delete adminWindow;
    adminWindow = NULL;
}

there is no need for private slots, all slots are public – 4pie0 Sep 17 '13 at 09:15 — 4pie0, Sep 17 '13 at 09:15
where is adminWindowClose definition? – 4pie0 Sep 17 '13 at 09:17 — 4pie0, Sep 17 '13 at 09:17
do a connect after pointer has been initialized – 4pie0 Sep 17 '13 at 09:18 — 4pie0, Sep 17 '13 at 09:18

score 0 · Accepted Answer · answered Sep 17 '13 at 09:18

0

You need to ensure that you're using valid adminWindow pointer on connect:

void MainWindow::on_ConfigureUsersBtn_clicked()
{
    if(adminWindow == NULL)
    {
        adminWindow = new AdministrativeWindow();
        connect(adminWindow, SIGNAL(windowClose()), this, SLOT(adminWindowClose()));
        adminWindow->show();
    }

answered Sep 17 '13 at 09:18

Nemanja Boric

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Ah, now I get this error after I moved the connect to on_ConfigureUsersBtn_clicked(): ASSERT failure in QWeakPointer: "Detected QWeakPointer creation in a QObject being deleted", file tools\qsharedpointer.cpp, line 1230 Invalid parameter passed to C runtime function. Invalid parameter passed to C runtime function. – Jarrod Cabalzar Sep 17 '13 at 09:37
I shoulod add that this doesn't occur until I trigger the close in the Admin window now, which is a better result than before because it would mean that the connect it (partially) working wouldn't it? – Jarrod Cabalzar Sep 17 '13 at 09:39
Don't worry, fixed it. Thank you for your help :) – Jarrod Cabalzar Sep 17 '13 at 11:50

4pie0 · Answer 2 · 2013-09-17T11:13:18.387

be sure to do a connect after pointer has been initialized

connect(adminWindow, SIGNAL(windowClose()), this, SLOT(adminWindowClose()));
           ^
        valid ptr

also private slots are private if called as regular member functions but always public for connection. I think this is cleaner design to define slots as public since their purpose is communication and use private functions as usual when they are needed unless you really need such mixed concept as private slot (it might exist however and one can imagine some special circumstances in which this might have sense, I assume this is not the case here)

Qt5 Connect Custom WindowClose Signal To A Different Window

2 Answers2