Re: Feature question: waiting on a plot window

[Daniel J S. <dan...@ie...>]

On 08/17/2018 03:15 PM, Dima Kogan wrote:
> Hi.
> 
> I'm looking for a feature that (I think) doesn't exist currently. Want
> to ask first, in case something DOES exist that I'm not seeing.
> 
> A number of applications that make plots use gnuplot as a backend. The
> sequence you want there is:
> 
> 1. User says "make a plot"
> 
> 2. Application tells gnuplot to make a plot
> 
> 3. gnuplot does its thing using an interactive terminal (x11, qt, wxt,
>     ...) and a plot window pops up
> 
> 4. user looks at the plot, then closes the window when they're done, and
>     wants to continue using the application
> 
> The issue here is that currently the application (parent of the
> "gnuplot" process) has no way of knowing when the user finished looking
> at the plot, which necessitates ugly workarounds. For instance with
> gnuplotlib I can write a script that just makes a plot. If I just call
> gnuplotlib.plot(), then the application will make a plot and then exit
> immediately. As a workaround I put a sleep(10000) after the plot() call.
> I'd like to have some sort of gnuplotlib.wait() that blocks until
> gnuplot is done. Maybe gnuplot can be asked to print something on the
> console when the client window is closed, or something? Thoughts?

Does "gnuplot --persist" work for your needs?  In the following, the 
gnuplot_qt process hangs around until the window is closed:

@linux ~ $ gnuplot --persist

	G N U P L O T
	Version 5.3 patchlevel 0    last modified 2018-04-26

	Copyright (C) 1986-1993, 1998, 2004, 2007-2018
	Thomas Williams, Colin Kelley and many others

	gnuplot home:     http://www.gnuplot.info
	mailing list:     gnu...@li...
	faq, bugs, etc:   type "help FAQ"
	immediate help:   type "help"  (plot window: hit 'h')

Terminal type is now 'qt'
Options are '0 font "Sans,9"'
gnuplot> system "ps -e | grep gnuplot"
  6680 pts/1    00:00:00 gnuplot
gnuplot> plot 1/x
gnuplot> system "ps -e | grep gnuplot"
  6680 pts/1    00:00:00 gnuplot
  6690 ?        00:00:00 gnuplot_qt
gnuplot> exit
@linux ~ $ ps -e | grep gnuplot
  6690 ?        00:00:00 gnuplot_qt
@linux ~ $ (manually close window)
manually: command not found
@linux ~ $ ps -e | grep gnuplot
@linux ~ $