Restarting a QML application

mzimmers

Hi all - I'm trying to adapt this approach for restarting a Qt application to one that doesn't use widgets. Here's what I've coded so far:

int main(int argc, char *argv[])
{
    int currentExitCode = 0;
    QGuiApplication app(argc, argv);
    MyClass myClass(nullptr, &app);
    QQmlApplicationEngine engine;

    qmlRegisterType<MyClass>("MyClass", 1, 0, "MyClass");
    engine.rootContext()->setContextProperty("myClass", &myClass);
    

    do {
        engine.loadFromModule("restartQml", "Main");  
        currentExitCode = app.exec();
    } while (currentExitCode == MyClass::EXIT_CODE_REBOOT);
    return currentExitCode;
}
//
class MyClass : public QObject
{
    Q_OBJECT
    QGuiApplication *m_app = nullptr;
public:
    explicit MyClass(QObject *parent = nullptr, QGuiApplication *app = nullptr);
    static const inline int EXIT_CODE_REBOOT = -123456789;

public slots:
    void restartRequested() {
        m_app->exit( EXIT_CODE_REBOOT );
    }

The problem is that the original instance of the app doesn't exit. Every time I press the restart button in the app, I get a new instance of the app, but the old one doesn't go away.

Can anyone tell me why the QGuiApplication isn't responding to the exit() call in the slot?

Thanks...

SGaist

Hi,

One key difference between your version and the one you linked, you are not recreating the QGuiApplication object nor the engine.

mzimmers

Thanks, @SGaist . It turns out that it was sufficient to recreate the engine. I modified the relevant portion of my code as follows:

    QQmlApplicationEngine *engine;

    qmlRegisterType<MyClass>("MyClass", 1, 0, "MyClass");

    do {
        engine = new QQmlApplicationEngine;
        engine->rootContext()->setContextProperty("myClass", &myClass);
        engine->loadFromModule("restartQml", "Main");
        currentExitCode = app.exec();
        delete engine;
    } while (currentExitCode == MyClass::EXIT_CODE_REBOOT);
    return currentExitCode;
}

And it seems to work fine.

I also discovered that I didn't need to pass in the QGuiApplication to my handler class; evidently this is provided to me via qApp:

#include <qguiapplication.h>
void MyClass::restartRequested()
{
    qApp->exit( EXIT_CODE_REBOOT );
}

Thank you for the help.