[Qt-interest] Exceptions caught in queued connections

[Gilles Valette]

Message de Santhosh Y <santhosh at softjin.com>:

>      Hi,
>
> Following is the message that Qt dumps when I am trying to catch the
> exception in a SLOT (queued connection).
> -------------------------------------------------------------------------
> Qt has caught an exception thrown from an event handler. Throwing
> exceptions from an event handler is not supported in Qt. You must
> reimplement QApplication::notify() and catch all exceptions there.
> -------------------------------------------------------------------------
>
> The following link exactly points to the problem I am facing now.
> http://lists.trolltech.com/qt-interest/2008-05/thread00942-0.html[1]
>
> The solution suggested is that, we need to reimplement
>  bool QCoreApplication::notify ( QObject[2] * /receiver/, QEvent[3] *
> /event/ )   [virtual]
>
> can anybody suggest me how to override the above function,
> so that my exceptions are handled in this function.
>
> I did not find event type as an Exception type so that I can handle
> or return from there!
>

Hi,

Here is an example of what you can do:

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

     bool notify( QObject * receiver, QEvent * event )
     {
         // try block
         try {
            // call to the ancestor's method
            return QCoreApplication::notify(receiver,event);
         }
         // if an exception is launched
         catch( myException &e ) {
             qDebug() << "Exception: " << e.what();
             return true;
         }
         catch( ... ) {
             qDebug() << "Unknown exception. Exit.";
             exit(1);
             //return true;
         }
     }
};

Hope this helps,

Gilles