RE: optional parm in CLLE

"Wrap" the old program with a new program (or procedure) that handles the variable. You're going to have to change every program that passes the new parameter, why not also change the name of the called program at the same time?

PrgA, PrgB, PrgC all call PrgZ with four parameters. You want to add a parameter when PrgB calls PrgZ. Have PrgB call PrgZ6 with the number of parameters in the first parameter. PrgZ6 calls handles the extra parameters and calls PrgZ with four after (or before) handling the extra parameters. PrgA and PrgC don't have to change. Having made that change to PrgZ6, you can continue to expand the number of parameters in the future without extending the wrapping.

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-
bounces@xxxxxxxxxxxx] On Behalf Of Briggs, Trevor (TBriggs2)
Sent: Monday, January 27, 2014 9:57 AM
To: Midrange Systems Technical Discussion
Subject: RE: optional parm in CLLE

This assumes that you know up front that you may have a varying number
of parameters. I suspect in many cases the requirement is to add a new
parameter to an existing CL program without the necessity of changing
every program that calls it.

Trevor Briggs
Analyst/Programmer
Lincare, Inc.
(727) 431-1246
TBriggs2@xxxxxxxxxxx

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Dan Kimmel
Sent: Monday, January 27, 2014 10:51 AM
To: Midrange Systems Technical Discussion
Subject: RE: optional parm in CLLE

The time-honored technique is to pass the number of parameters in the
first parameter.

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-
bounces@xxxxxxxxxxxx] On Behalf Of Briggs, Trevor (TBriggs2)
Sent: Monday, January 27, 2014 7:29 AM
To: midrange-l@xxxxxxxxxxxx
Subject: RE: optional parm in CLLE

Barbara,

I have used a similar function in the past (using the "optional"
parameter name in the CHGVAR FROM rather than the TO variable), and I
was unaware of the fact that false positives could occur. I suppose if
there were a limited number of acceptable values for the parameter

that

you could check against then the chances of "accidentally" finding

ones

of these in a "phantom" parameter would be negligible. But in cases
where the parameter values could be a large number of values it seems
from this thread that IBM gives us NO 100% reliable way of determining
the number of parameters passed to a CL program. Is that so?

Thanks,

Trevor Briggs
Analyst/Programmer
Lincare, Inc.
(727) 431-1246
TBriggs2@xxxxxxxxxxx
-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Barbara Morris
Sent: Friday, January 24, 2014 7:31 PM
To: midrange-l@xxxxxxxxxxxx
Subject: Re: optional parm in CLLE

On 1/24/2014 8:29 AM, Alan Cassidy wrote:

I just did this:
CHGVAR&VALUE3&PARAMETER3
MONMSG MCH3601 EXEC(DO)
SNDPGMMSG MSG( 'Did not receive 3 parameters') TOPGMQ(*EXT)
ENDDO
ENDPGM

Worked at least.

I just want to make sure that it's clear that this technique should
absolutely never be used.

It often seems to work in testing, but it's almost guaranteed to give

a

false positive at some point, indicating that a parameter was passed
when it wasn't.

What's especially bad about this technique is that if your program
modifies a parameter that was not actually passed, you can cause

bizarre

and unpredictable errors that might show up long after your program

has

returned.

--
Barbara
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