Re: Reworked qt terminal is much faster – and fails to work on Mac

[Thomas B. <Tho...@gm...>]

* Daniel J Sebald <dan...@ie...> [2014-02-12 06:36]:
> In any case, I suggest adding the sleep as Ethan has done.  There is
> no reason that should be running at 100%.  In fact, there is
> probably a preferred way to do this without polling loops.  I
> learned a little bit about Qt working on Octave and Qt has this
> paradigm of signals and slots and the developers suggest adhering to
> the concept otherwise can get kind of dodgy (not in this simple
> case...but cases where widget IDs are floating about).
> 
> signal:  something that a Qt object emits
> slot:  the destination of the signal which can
>        be of any number, e.g., five other
>        objects could connect a slot to a signal
> 
> Anyhow, I don't have time to look at this right now, but if one
> looks at the documentation for a Qt socket:
> 
> http://qt-project.org/doc/qt-4.8/qlocalsocket.html#connectToServer
> 
> it indicates that a signal is emitted when the connection is
> complete and there is a signal emitted when there is an error.  So
> the proper thing to do is to first make connections to the socket
> sort of like the following ("success" and "failed" are custom member
> functions):
> 
> connect (createdsocket, SIGNAL (connected ()), watcher, SLOT (success ()));
> connect (createdsocket, SIGNAL (error ()), watcher, SLOT (failed ()));
> 
> and then tell the socket to attempt to connect to the server:
> 
> createdsocket->connectToServer (name)
> 
> There is no need to check in a loop for anything.  Either the socket
> will successfully connect and emit "connected" at which point
> "success()" will get called or the socket will timeout and emit
> "error" at which point "failed()" will get called.
> 
> One can get very creative about connections made, the number of
> slots watching a signal, doing this dynamically, etc.  So instead of
> a recursive routine, it might be multiple connections, or
> dynamically reconnect/disconnect in the "failed()" slot.  Etc.

signals and slots are indeed very nice, but they need a Qt event loop to
work correctly. I don't think it is possible to add the Qt event loop to
gnuplot without major surgery. (Well, you can start a local event loop
using QEventLoop inside a function, but in this case it's just more work
to get the same result we already have).

Thomas