[Qt-interest] QtConcurrent::Exception

[Niklaus Hersche]

It could be done that way. But the idea of throwing everywhere and catching
in one place, has 

certainly its attraction and leads to less code and more flexibility.

 

Cheers

Nik

 

 

  _____  

Von: Sylvain Pointeau [mailto:sylvain.pointeau at gmail.com] 
Gesendet: Donnerstag, 7. Mai 2009 16:36
An: Niklaus Hersche
Cc: qt-interest at trolltech.com
Betreff: Re: [Qt-interest] QtConcurrent::Exception

 

why don't you catch your exception from the specified thread and send an
event to your main thread?
you should really avoid thinking exceptions with threads.

Cheers,
Sylvain



On Thu, May 7, 2009 at 4:25 PM, Niklaus Hersche <niklaus.hersche at gesys.ch>
wrote:

Hi,

Thanks for answering.

Meanwhile i figured out how to do it.


It only works, if you throw the exception from within an eventhandler.
This presupposes, that the thraed has an eventloop ( call exec()).

You can try/catch in QApplication::notify

e.g:
************************************************************
virtual bool notify(QObject *p_sender, QEvent *p_event) {
 try {
   return QApplication::notify(p_sender, p_event);
 }catch(const MyXeption &e) {
   QThread *currentThread = QThread::currentThread();
   if(currentThread != thread()) {
     // l'exception à été lancé dans une autre thread
     // il n'est donc pas possible d'afficher d'éléments graphique ici ...
     qDebug() << "MyXeption caught:" << e.what();
   } else {
     // l'exception à été lancé dans la thread principale
       // on peut donc afficher un dialog ...
     qDebug() << "MyXeption caught:" << e.what();
   }
 }
}
************************************************************
See also http://forum.qtfr.org/viewtopic.php?id=7615

Cheers
Nik

________________________________________
Von: Sylvain Pointeau [mailto:sylvain.pointeau at gmail.com]
Gesendet: Donnerstag, 7. Mai 2009 15:31
An: Niklaus Hersche
Cc: qt-interest at trolltech.com
Betreff: Re: [Qt-interest] QtConcurrent::Exception


I don't think that the exceptions in C++ can be thrown in one thread and
catched in another.

Cheers,
Sylvain
On Wed, May 6, 2009 at 2:18 PM, Niklaus Hersche <niklaus.hersche at gesys.ch>
wrote:
Hi,

In a worker thread I want to throw a QtConcurrent::Exception and catch it in
the main thread.


According the documentation,

" Base class for exceptions that can transferred across threads"

this should be possible.

Does anybody know how to implement it ?


Regards
Nik


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