Re: Qt/gui on MacOSX

[Daniel J Sebald]

On 11/05/2012 05:55 PM, Michael Goffioul wrote:

> If there was a clean way
> to dissociate from current terminal and re-attach to another PTY without
> forking, I'd be more than happy to use it, but I haven't find such solution
> so far.
>
> Gnuplot's problem is the opposite: running a GUI in a separate/child
> thread, while the CLI is running in the main thread. This is not possible
> under Mac OS X. The only solution is to run the CLI as a separate thread
> and keeps the GUI in the main thread, which is what we do, but we end up to
> a another related Mac OS X limitation.

The author of the Qt driver for gnuplot believes that the Qt driver can 
be done without fork.  Unfortunately, no one on gnuplot developer list 
uses Windows so the concept can't be tested thoroughly unless someone 
with a Windows machine volunteers to assist a little.  A dearth of 
Windows users in this Octave Maintainers List is also a problem.

So if avoiding the fork could be accomplished and OS X were to use the 
Qt driver instead of X-windows driver, that might partially simplify things.


> > In any case, if you come up with some alternative that allows running
> > a only single process on OSX I'd very much like to hear about it.
> > I was never able to find an OSX guru who could produce such a creature.
>
> In our case, I think what may work (not tested) is to re-exec octave after
> the fork with some special argument to avoid re-fork'ing.

Whatever the solution, I think it would be good to start out keeping the 
three major operating systems in mind (sorry if I overlooked one) even 
though we don't have any Windows developers.  It seems to me the best 
way to accomplish this in a portable fashion is for Qt to have a feature 
for executing subprocesses.  There is this QProcess:

http://doc.qt.digia.com/qt/qprocess.html

that appears to have a lot of member functions.

This will require some thought as right now the terminal doesn't seem to 
work so well inside the GUI, but that might not be the communication's 
fault.  I do know that if STDERR is not redirected to the terminal 
window, the Octave pager won't work correctly.  That may complicate things.

Dan