Re: eliminating GUI event listener class

[Daniel J Sebald]

On 04/08/2013 11:23 AM, John W. Eaton wrote:
> The only thing we are using the event listener object for is to
> handle cleaning up the GUI when we exit from Octave. I tried to
> switch that to using signals and slots but was not successful.
>
> Can anyone explain the proper way to exit a Qt application like the
> one we have with multiple threads? Where does qtApp->quit need to be
> called?

My guess is that you are issuing a signal from inside the Octave 
executable, which triggers the Octave thread to close, then returning to 
that code (no longer running) causes the crash.  (The event listener 
approach initiates the closing of the application from the GUI thread side.

There is probably a better way.  Simply let Octave thread finish or 
terminate.  There is a signal that is issued by the thread which can be 
connected to something on the GUI side before the Octave thread is started:

http://qt-project.org/doc/qt-4.8/qthread.html#finished
http://qt-project.org/doc/qt-4.8/qthread.html#terminated

Create a slot that will close the GUI upon getting one (or both?) of 
those signals.  Right now, GUI/IDE isn't saving modified files, so 
something needs to be fixed there.

Dan