[Qt-interest] How to handle exceptions in Qt

[Santhosh Y]

Hi,

In following snippet, I purposefully made a widget to NULL, and calling 
a function on that.
It is crashing the moment it access a fn on that NULL pointer.

But my expectation was that, control will reach catch(...) and then 
printing  std::cout statement.
But I am not seeing this message on my console.

To catch the exceptions, I also overridden QApplication::notify(). It is 
also not helping!

What is the issue here ?

------------------------------------------------------------------------------------------------------ 

------------------------------------------------------------------------------------------------------ 


/// QApplication derived class
class MyApp : public QApplication
{
    Q_OBJECT

    public:
        MyApp(int& argc, char **argv) : QApplication(argc,argv) {}

        bool notify( QObject * receiver, QEvent * event )
        {
            try {
                // call to the ancestor's method
                return QApplication::notify(receiver,event);
            }
            catch( ... ) {
                std::cout << "Unknown exception. Exit." << std::endl;
                exit(1);
            }
        }
};

/// QMainWindow derived class
class Launcherview : public QMainWindow {};


/// Function throwing the EXCEPTION
void
LauncherView::createTopDockWidgetArea ()
{
      try {
        // Creation of DockWidget
        QDockWidget* mainWndwTaskBar = new QDockWidget();

       // purposefully made it to NULL; to check whether exception is 
caught ?
       mainWndwTaskBar = NULL;

        // setting no dock features
        mainWndwTaskBar->setFeatures (QDockWidget::NoDockWidgetFeatures);

    } catch (...) {
        std::cout << "Exception Caught ..... " << std::endl;
        throw;
    }
}


/// It was crashing in the following API of Qt infrastructure which is 
CORRECT.
/// Qt DockWidget class
void QDockWidget::setFeatures(QDockWidget::DockWidgetFeatures features)
{
    Q_D(QDockWidget);
}



-- 
----------------------------------------------------
Y Santhosh Kumar - 
Senior Software Engineer,
SoftJin Technologies Pvt Ltd,
www.softjin.com
----------------------------------------------------



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