Unless there is a reason to handle a nonzero rc (e.g. error correction
code, or special a special message), then Phil's simple example would be
better handled with an existing rexx convention:
Signal ON ERROR
address command 'somecmd'
...
then either leave Signal ON ERROR active - generally not a bad setting
unless you are specifically planning to accept and handle nonzero return
codes, or issue: Signal OFF ERROR. (Forgive the mixed-case emphasis - I
prefer to emphasize the potential for logical path flow changes.)
Signal ON ERROR (along with Signal ON SYNTAX, and Signal ON NOVALUE) will
help identify failures in code that may otherwise require significant
debugging. Actually, I seem to remember Phil suggesting them in the past?
Rexx provides help when asked -- let it.
Mike Walter
Hewitt Associates
The opinions expressed herein are mine alone, not my employer's.
"Kris Buelens" <kris.buel...@gmail.com>
Sent by: "The IBM z/VM Operating System" <IBMVM@LISTSERV.UARK.EDU>
02/25/2010 09:06 AM
Please respond to
"The IBM z/VM Operating System" <IBMVM@LISTSERV.UARK.EDU>
To
IBMVM@LISTSERV.UARK.EDU
cc
Subject
Re: An SFS aid
2010/2/25 Phil Smith III <li...@akphs.com>
......
Another great use for SIGNAL (and one that your rules do admit to) is for
error exits. I hate code like this:
address command 'somecmd'
if rc <> 0 then do
say 'That was an error, rc='rc
exit rc
end
Far better IMHO is:
address command 'somecmd'
if rc <> 0 then signal Error
This keeps the mainline more compact and readable, and it's pretty clear
to the reader that "Hey, we're going somewhere to handle the error and we
ain't comin' back"!
We now return you to the actual thread on SFS.
...phsiii
I agree with the "use Signal sometimes", in cases where one will not
return, it is more clear indeed. But, the example above "if rc<>0 then
signal Error" isn't very practical: you cannot pass parameters. So I have
a Call to my errorexit: routine. The name of the called routine makes it
clear to the reader that one will not return from there.
if rc<>0 then call errExit rc,'Something was wrong','Please try again'
.......
ERREXIT: /* general errorexit routine */
parse upper source . . myname .
do i=2 to arg() /* give errormessages (if any) */
say myname':' arg(i)
end
exit arg(1)
I guess we devoted some chapter to it in our selfstudy Telecourse:
http://www.vm.ibm.com/download/packages/descript.cgi?TCVM1
--
Kris Buelens,
IBM Belgium, VM customer support
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