RE: Procedure PR/PI question

"Now we may all agree that using global variables is evil, but up to
V5R4 (just a few months, just a few months, ...) files had to be global.
That means that all programs written before 6.1 that use files (that
might be quite a few) have a lot of global variables."

Just because the files needed to be global doesn't mean the global
fields needed to be used.

On v5r4 Any sub-procedure could locally define a external qualified data
structure for input or output and then use that on all file input and
output.

D InputDS E DS EXTNAME(filename:*INPUT) qualified
READ Filename InputDS;

Using that type of data structure the sub-procedure could "protect" its
access to the data and not affect the globally defined fields.

Just because the global field is there doesn't mean it's a good idea to
use it.
Which means it's up to the programmer to choose to use the global fields
or define the field locally to the procedure.


Chris Hiebert
Programmer/Analyst
Disclaimer: Any views or opinions presented are solely those of the
author and do not necessarily represent those of the company.

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Joep Beckeringh
Sent: Monday, April 29, 2013 5:53 PM
To: RPG programming on the IBM i (AS/400 and iSeries)
Subject: Re: Procedure PR/PI question

I think the point 'what sson' was trying to make, was that passing a
global variable as a CONST parameter to a local subprocedure can get you
in trouble, as the procedure changes the global variable. Now we may all
agree that using global variables is evil, but up to V5R4 (just a few
months, just a few months, ...) files had to be global. That means that
all programs written before 6.1 that use files (that might be quite a
few) have a lot of global variables.

If you use an input field as a CONST parameter to a local procedure and
that procedure (or another local procedure that is called by this
procedure) reads another record in the same file, your CONST parameter
suddenly changed. So I can understand what sson's feelings about using
VALUE for local procedures.

Joep Beckeringh