[Qt-interest] QtConcurrent and QFutureWatcher

[Andre Somers]

  Op 23-9-2010 14:35, Marius Roets schreef:
> Hi Everybody,
>
> I have this piece of code in a widget, when a button is pressed:
>
> MyObject m;
> QFutureWatcher<void> futureWatcher;
> connect(&futureWatcher, SIGNAL(finished()), this, 
> SLOT(longExecuteCompleted()));
> futureWatcher.setFuture(QtConcurrent::run(m, &MyObject::longExecute));
>
> It seems to work as expected, except that longExecuteCompleted() never 
> gets called, and I can see from the log files that longExecute() did 
> complete. Is there anything I could missing in MyObject, longExecute() 
> or futureWatcher for this to work.
The issue is, that your futureWatcher goes out of scope before the 
execution of your longExecute is finished. That means that the 
futureWatcher is destroyed, and the connection deleted. Put your future 
watcher somewhere where it will last long enough to actually signal the 
completion of your task, like on the heap (don't forget to delete it 
when you're done using it) or as a member of your object.

André