Re: Is gp_exit() used at exit in current gnuplot?

[sfeam <sf...@us...>]

On Tuesday, 28 February 2017 02:57:46 PM Tatsuro MATSUOKA wrote:
> ----- Original Message -----
> 
> > From: sfeam 
> > To: gnuplot-beta Tatsuro MATSUOKA 
> > Cc: 
> > Date: 2017/2/28, Tue 13:51
> > Subject: Re: Is gp_exit() used at exit in current gnuplot?
> > 
> > On Tuesday, 28 February 2017 10:38:04 AM Tatsuro MATSUOKA wrote:
> >>  This is related to bug #1913.
> >> 
> >>  In stdfn.c
> >> 
> >>  there stated
> >> 
> >> 
> >>  /* Calls the cleanup functions registered using gp_atexit().
> >>   * Normally gnuplot should be exited using gp_exit(). In some cases, this 
> > is not
> >>   * possible (notably when returning from main(), where some compilers get
> >>   * confused because they expect a return statement at the very end. In that
> >>   * case, gp_exit_cleanup() should be called before the return statement.
> >>   */
> >> 
> >> 
> >>  *****************************
> >>  Normally gnuplot should be exited using gp_exit().
> >>  ***************************
> > 
> > I think the intended meaning is
> > "If you were going to terminate the program by calling exit(), don't do 
> > that.
> > Instead call gp_exit()."  
> > 
> > However the normal exit from main() in a C language program is by 
> > "return", not "exit()". 
> > So gnuplot's main() routine does not  call either exit() or gp_exit().  
> > Instead it calls
> > gp_exit_cleanup() followed by "return". 
> > Thus it does exactly what the comment describes.  
> > 
> >>  Excuse me for my writing without reading the code in detail.
> >>  gp_exit() seems to be used in many place in the code.
> >>  Therefore gp_exit() is surely used in current gnuplot.
> > 
> > Yes.  For example If you say
> > gnuplot>  exit gnuplot
> > then it calls gp_exit().
> > 
> >>  However, "gnuplot> exit" does not use gp_exit() as written in 
> > the
> >>  previous post.
> >> 
> >>  I feel that the message
> >> 
> >>  Gnuplot not exited using gp_exit(). Exit handlers may not work correctly!
> >> 
> >>  in debug_exit_handler in stdfn.c is better to be modified.
> > 
> > I think you are correct that the message is not accurate.
> > It would be better to say 
> > "Gnuplot not exiting normally. Exit handlers may not work correctly!"
> > gp_exit() is one way of exiting normally, but exiting by return from main()
> > is also a way of exiting normally.
> > 
> > In your case (Bug 1913) I guess neither of these normal ways to exit is 
> > happening.
> > Instead gnuplot is killed by the operating system because you hit  the "X 
> > button".
> > 
> >     Ethan
> > 
> > 
> > 
> Thank you for your comprehensive explanation.
> I hope that message  in debug_exit_handler will be modified as you indicaded
> 
> "Gnuplot not exiting normally. Exit handlers may not work correctly!"


OK.  It now says:
    "Gnuplot exiting abnormally. Trying to execute exit handlers anyway."

So far as I can see, the only purpose of this message is to help debug
the exit sequence, like you are doing with Bug 1913.

	Ethan