[PATCH] plot.c, setjmp question

[<tim...@en...>]

Hi!

I've been working on some code to rework some parts of gnuplot main loop
and initialization (mostly to address
wxt-on-mac-is-better-when-singlethreaded and the issues with handling
events from multiple interactive terminal at the same time).

I've come to think about the setjmp/longjmp mechanism for error handling.
It works perfectly fine in its current state, but I was wondering if there
could be some cleanup in plot.c:main(). In particular, from 'man setjmp':

NAME
       setjmp, sigsetjmp - save stack context for non-local goto
RETURN VALUE
       setjmp() and sigsetjmp() return 0 if returning directly, and
non-zero when returning from longjmp(3)  using  the  saved context.


So, I conclude that any code executed conditionally to !setjmp(...), if
not changing the stack, could be put before the call to setjmp and give
exactly the same behaviour. In other words:

if(!setjmp(...))
{
    /* setjmp returns direclty */
    code_that_does_not_change_the_stack();
}
else
{
    /* coming back from longjmp */
}

is strictly equivalent to:

code_that_does_not_change_the_stack();
if(setjmp(...))
{
    /* coming back from longjmp */
}

Am I right ?

If yes, is the attached patch correct and ok for CVS ? (it would allow
more generalization of the error mechanism)

Thanks for your comments.
Best regards,

Timothée