I include the following code in every REXX EXEC that I code. It’s taken from a
great article by Walter Pachl, IBM Retiree, entitled, “What's wrong with Rexx?”
You can find it at…
www.rexxla.org/events/2004/walterp.pdf
So at the top of the code, I have…
/* REXX */
SIGNAL ON NOVALUE /* Enable the conditions and */
SIGNAL ON SYNTAX /* point at reasonable */
SIGNAL ON FAILURE /* condition handling */
SIGNAL ON HALT
Then at the bottom, I have…
/*
Condition handling
Taken from "What's wrong with Rexx?" by Walter Pachl, IBM Retiree
Downloaded from www.rexxla.org/events/2004/walterp.pdf
*/
NOVALUE:
SAY 'Novalue raised in line' SIGL /* line in error number */
SAY SOURCELINE(SIGL) /* and text */
SAY 'Variable' CONDITION('D') /* the bad variable reference */
SIGNAL Lookaround /* common interactive code */
SYNTAX:
SAY 'Syntax raised in line' SIGL /* line in error number */
SAY SOURCELINE(SIGL) /* and text */
SAY 'rc='rc '('errortext(rc)')' /* the error code and message */
HALT:
Lookaround: /* common interactive code */
/* IF user_interface = 'FORE' THEN DO when running in foreground */
SAY 'You can look around now.' /* tell user what he can do */
TRACE ?R /* start interactive trace */
NOP /* and cause the first prompt */
/* END */
ctr.return_code = 16
SIGNAL Quit
As Walter pointed out in his article, having this code prevents a lot of
debugging headaches.
Also, Paul Gilmartin mentioned the SYMBOL(name) function which will tell you if
a variable has a value assigned. There is also the DATATYPE function which
will tell you the type of data the value is.
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