Re: es signal catching

[Donn Cave <donn@u.washington.edu>]

|> It seems to me that I want to be able to "catch" these exceptions in the
|> doit() loop, but I can't see how to do that.

| the other thing you have to do is add the signals you want to
| catch to the list $signals.  no promises that it works, but it
| has been tested a little.  please let me know whether it works.

Well, yes, that part I (sort of) had figured out, and it works as far
as it goes:

	;; signals = ($signals sigusr1)
	;; kill -USR1 $pid
	uncaught exception: signal sigusr1
	;;

So, since it's not getting any clearer to me how to install a signal handler
for the main read/eval loop, I added a couple of lines to doit() to see if I
could add support for rc's "fn sigxxx" convention.  It seems to work, and I
include the code below.  Still, I would much rather use es as distributed,
if anyone can clue me in as to how.

	Donn Cave, University Computing Services, University of Washington
	donn@cac.washington.edu
-------------------------------
	caveat:
	The following was done in haste, by someone who has virtually no
	idea how es' memory management works.
----------------------------------------
*** input.c.v2	Tue Oct 20 15:59:01 1992
--- input.c	Mon Dec 21 15:36:16 1992
***************
*** 299,304 ****
--- 299,305 ----
  		execit = FALSE;
  
  	while ((e = pushhandler(&h)) != NULL) {
+ 		List *signalfunc;
  		if (!interactive) {
  			popinput();
  			throw(e);
***************
*** 305,310 ****
--- 306,313 ----
  		}
  		if (streq(getstr(e->term), "error"))
  			eprint("%L\n", e->next, " ");
+ 		else if (streq(getstr(e->term), "signal") && (signalfunc = varlookup2 ("fn-", e->next->term->str)))
+ 			eval(mklist(signalfunc->term, e->next), NULL, TRUE, exitonfalse);
  		else if (!issilentsignal(e))
  			eprint("uncaught exception: %L\n", e, " ");
  	}