RE: subprocedure questions

In V5Rx (5.1 I think) the LIKEDS keyword does what we wish the old LIKE
keyword did. That is, it actually declares another data structure with
the same subfields as the based-on data structure. Whereas the old LIKE
keyword simply created a character field with the same length as the
data structure--no subfields included. :(   This was the only way to do
this kind of thing, until V5, however.

Bob Cozzi

-----Original Message-----
From: rpg400-l-admin@midrange.com [mailto:rpg400-l-admin@midrange.com]
On Behalf Of Haas, Matt
Sent: Thursday, November 07, 2002 8:42 AM
To: rpg400-l@midrange.com
Subject: RE: subprocedure questions

Dan,

If you look (and unless I mis-keyed something) both data structures are
the same except for the names. The reason for this was to give the
subprocedure it's own copy of the data structure to work with so you
don't run into problems with scope. I could have easily updated the
variables in MyDS directly, eliminating the need to even return anything
but that's a bad thing to do since it makes the code very hard to debug,
but this keeps it more modular so if you need to, it can be broken out
into a service program.

Matt
-----Original Message-----
From: Dan [mailto:dbcerpg@yahoo.com]
Sent: Thursday, November 07, 2002 9:28 AM
To: rpg400-l@midrange.com
Subject: RE: subprocedure questions


I'm going to give that a try.

Question:  In your PI (Procedure Interface), you use LIKE(MyDS), but
the data structure below defines MyDS2.  Was that intentional?  Or
would you just as soon use MyDS2?  Does the subprocedure "see" all the
variables in the main module?

TIA, Dan

--- "Haas, Matt" <Matt.Haas@thomsonlearning.com> wrote:
> Dan,
>
> There's two way's to do this, the first is to remove the 'VALUE' from
> Z_ACGAMT and Z_AMTERR which passes the variable by reference instead
> of by value so you can modify it in your subprocedure. Passing by
> value (which is what you do when you add VALUE to a parameter
> definition) is similar to declaring a constant in that you can't
> change it in the subprocedure.
>
> A better way would be to create a data structure for these two values
> and return the data structure just like you would when dealing with
> API's. This makes the program much easier to maintain if you need to
> return another field in the future. To do this, you'd do something
> like this:
>
> DMyDS             DS
> D Z_ACGAMT                       8S 2
> D Z_AMTERR                      30A
>
>
> D CVTA2N          PR                  LIKE(MyDS)
> D   ACGAMT                      10A   VALUE
>
> C               eval     MyDS = CVTA2N(ACGAMT)
>
> P CVTA2N          B
> D CVTA2N          PI                  LIKE(MyDS)
> D   ACGAMT                      10A   VALUE
>
> DMyDS2            DS
> D   X_ACGAMT                     8S 2
> D   X_AMTERR                    30A
> <snip>
> C    .........  EVAL      X_ACGAMT = N_ACGAMT
> C    .........  RETURN    MyDS2
> P                 E
>
> Matt

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