Connecting signal from main.cpp to application.cpp

[Jon Heron]

Excuse my c++ ignorance.
I am trying to attach the QCoreApplication::aboutToQuit() signal to my save function so I can save some data after the user closes the app on BB10 OS. My QCloseEvent doesn't get called on BB10 when the user swipes up and closes the app so I am trying this approach as suggested in the docs for BB10.
According to the docs for BB10 I have 3 seconds after the signal aboutToQuit() is emited which should be plenty of time for QSettings to save my data.
I put this line in my main.cpp

QObject::connect(&a, SIGNAL(aboutToQuit()), &w, SLOT(save()));

QObject::connect(&a, SIGNAL(aboutToQuit()), &w, SLOT(save()));

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Here is my entire main.cpp for referance:

#include <QtGui/QApplication>
//#include <QtGui/QGuiApplication>
#include "biologger.h"
//#include <bb/Application>
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
 
    a.setOrganizationName("HeronBoy");
    a.setOrganizationDomain("theHerons.ca");
    a.setApplicationName("Bio Logger");
 
    bioLogger w;
    w.showMaximized();
    QObject::connect(&a, SIGNAL(aboutToQuit()), &w, SLOT(save()));
    return a.exec();
}

#include <QtGui/QApplication>
//#include <QtGui/QGuiApplication>
#include "biologger.h"
//#include <bb/Application>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    a.setOrganizationName("HeronBoy");
    a.setOrganizationDomain("theHerons.ca");
    a.setApplicationName("Bio Logger");

    bioLogger w;
    w.showMaximized();
    QObject::connect(&a, SIGNAL(aboutToQuit()), &w, SLOT(save()));
    return a.exec();
}

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But my save function is never called?
The way I understand it the signal should be accessible from any public slots in the application and I have my save function declared as a pubic slot

public slots:
    void save();

public slots:
    void save();

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.

Any help or insight on how to troubleshoot this would be appreciated.
Cheers,
Jon

[anda_skoa]

Do you get any runtime error at startup, i.e. does the connect work (it will print a warning if it does not).
It looks good but e.g. the class bioLogger could miss the Q_OBJECT macro, etc.

Another option you could try if you don't need the event loop

w.showMaximize()
 
int ret = app.exec();
 
w.save();
 
return ret;

w.showMaximize()

int ret = app.exec();

w.save();

return ret;

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Cheers,
_

[Jon Heron]

Thanks!
No, there is no error messages, not sure what the problem is... Is there any way to qDebug() << the signal from the app.cpp to see if its getting emitted?
Either way your event loop works great and its now saving properly!
Thanks again!
Cheers,
Jon

[anda_skoa]

No, there is no error messages, not sure what the problem is... Is there any way to qDebug() << the signal from the app.cpp to see if its getting emitted?

Not without changing Qt I think.

Either way your event loop works great and its now saving properly!

Ah, great

Cheers,
_

[Lesiok]

Read about QSignalSpy class.

[Radek]

The usual way of checking whether a slot is called is putting a break (or qDebug() or something similar) in the slot handler and seeing whether you reach the breakpoint (or whether you get a message or something similar). If you cannot modify bioLogger then create a class, say DebugClass, give the class a slot, say DebugSlot() and connect the signal to the DebugSlot(). Put qDebug() in the DebugSlot() and let DebugSlot() call w.save(). Run and see what will happen.