RE: Change a VALUE parameter

Hi Jeff,

Const = parameter is passed by reference (so it's a pointer to an
address). The value at that address cannot be changed.

Value = parameter is passed by value (so it's passing the actual value
not the pointer). The procedure then receives a _copy_ of that
parameter to do with as it pleases. Whatever the procedure does with
that parameter will not be reflected in the calling procedure.

So Value is a way to pass a variable or constant to a procedure and
being guaranteed that what gets passed won't get changed by that
procedure - even though the procedure can change the parameter.

As far as passing in different sizes (like 7p1 into a 7p2)... I know
that works with Const, though I'm unsure about Value.

Kurt Anderson
Application Developer
Highsmith

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Jeff Crosby
Sent: Thursday, September 18, 2008 8:15 AM
To: RPG400 Discussion List
Subject: Change a VALUE parameter

All,

I got something unexpected compiling a service program and am intrigued.

I defined one of the parms in the procedure interface like this:

D ASLPC 7P 2 Const

since I change the value of that field in the called procedure, the
compiler told me that was a no-no. Just for fun, I changed it to this:

D ASLPC 7P 2 Value

Now it compiles! Is this working as designed? I can pass decimal parms
as VALUE, they can be different sizes in the caller/callee, and the
compiler handles it? The calling program gets back the changed value,
decimal aligned and everything?

I'm going to try some experimenting, but I just didn't think this would
work on parms that get changed.

--
Jeff Crosby
UniPro Foodservice/Dilgard
260-422-7531
Opinions expressed are my own and not necessarily those of my company.
Unless I say so.