Re: Questions about quitting Octave and exit confirmation dialog

[Daniel J Sebald]

On 10/28/19 3:38 PM, John W. Eaton wrote:
> I'm trying to improve the way Octave behaves when exiting and would like 
> to understand what Matlab users might expect.
>
> Does Matlab offer a "confirm before quitting" option for its GUI?

Not sure, but there could be a confirm quit the first time and then a 
box "don't ask anymore" to check.


> Does that action work when quit is called from a function, or only when 
> it is executed at the command line or when Matlab is closed using some 
> "exit applcation" button in the GUI?
>
> If confirmation is requested when the quit function is called from a 
> function, what does the quit function do?  Here is an example:
>
>    function myquit ()
>       quit;
>       disp ('foo-i-hithere');
>    end
>
> If you call this function and a quit confirmation dialog is shown and 
> quitting is NOT confirmed, does execution continue immediately after the 
> call to "quit" so that the message displayed?  Or does execution resume 
> at the top-level command prompt with no message displayed?  I'm trying 
> to determine whether the quit function interrupts the execution of a 
> program (similar to Control-C) even if the quit action is not confirmed.

A few years back I worked hard to make all the 'quit' stuff more 
conventional, but it was kind of tricky.  I remember there being a 
particular snag, but I can't recall what it is.  I became busy with 
other things.  But there is a patch at this bug report:

https://savannah.gnu.org/bugs/?44485#comment44

There is a pretty common convention (and Windows might do this 
automatically) of confirming quit and if the application is busy put up 
a different type of dialog box like "not responding".  So involved in 
this is to tell the core worker thread to exit.  But if the core is busy 
computing pi to 5 million decimal places, then a timer in the GUI 
expires and asks if the user wants to end that process.  So, then there 
is properly shutting down a thread to deal with.  THEN, if the timer 
times out and the dialog is visible, say the worker thread finishes its 
task and responds to the exit, the dialog should go away and the GUI 
exit.  So there needs to be a signal/slot connection from the worker 
thread to the "shut-down" dialog.  Also, there could be multiple exit 
requests.  As I said, it's tricky.  It's probably dependent on how Qt 
signal/slot friendly the overall design is.

Dan