On Fri, 11 Jan 2019 20:58:51 +0000, Seymour J Metz wrote:
>FSVO goto that lives in a different universe from PL/I. The REXX signal
>statement trashes the stack rather than simply popping it appropriately.
>Consider
>
SIGNAL trashes the DO nest but it does not update the CALL/RETURN stack. I
encountered
this to my dismay working with code of a co-worker who relied on SIGNAL to
exit a
funtion by branching to the top of a DO on an error condition. Worked when he
tested
it; overflowed CALL/RETURN stack on a large production data set.
Rexx sorely lacks LONGJUMP for this purpose. (An extension to ITERATE/LEAVE
would
suffice and be better structured.)
>do I=1 to n
> do j=1 to m
> ...
> if foo then signal bar
> ...
> end
> ...
> bar:
> ...
> end
Rather, I'd propose:
do I=1 to n
do j=1 to m
...
call F
...
end j /* I label ENDs whenever possible. */
...
bar:
...
end I
return
F: procedure expose I
...
if foo then iterate I
...
return
--gil
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