Re: [Plplot-devel] qt_example memory management issues (SOLVED!)

[Alan W. I. <Ala...@gm...>]

Hi António:

Thanks for your recent replies concerning my Qt5 education
and also your successful tests of the previous commit.

With commit plplot-5.14.0-16-g02652c9a4 I am virtually positive from
valgrind results that I have solved these qt_example memory management
issues while still being able to properly delete the PLplot library
and the PlotWindow instance.  See that commit message for details.

The comprehensive test for that commit did not turn up any segfaults
for the first time ever!  However, that test did turn up an
intermittent hang for qt_example on exit similar to what I found in
December for pyqt5_example (but no hang for pyqt5_example this time
although that example is unchanged).  But in this case, I
could prove the hang was because the exec method for the qApp
never returned control to the main routine of qt_example.

See the commit message for documentation I discovered with a google
search of the recommended signals and slots procedure for making the
current problematic cleanup procedure completely robust and possibly
solving these intermittent hang on exit problems

I suspect this recommended and documented change is a matter of 15
minutes or so for someone who is expert in Qt5.  But that is not me.
(For example, I am just learned about Qt signals and slots today.)  Of
course, I am retired so I have much more time than the rest of the
PLplot developers here to work on PLplot.  So if you (or someone else
here with Qt5 expertise) don't have time/inclination to fix this
according to the web prescription I have documented, I do plan to do
it myself after a substantial break to work on PLplot components that
are a lot easier for me!

Alan
__________________________
Alan W. Irwin

Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
__________________________

Linux-powered Science
__________________________