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

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

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





 
> Tatsuro