AW: Assembly programmers do it a byte at a time

Hi guys,

sometimes I use subroutines to make my code more readable,
i.e. programming a subfile with a confirmation subfile,
that works like SAA-Standard.

I'd never create a procedure, that cannot be encapsulated.
To simply replace BEGSR through a P-statement
and only use global variables does not make sense, in my opinion.

A procedure or function must be encapsulated and only use local variables
(with the exception of file information defined in the F-Specs).
Because files defined in the F-Specs are always global,
I prefer to use embedded SQL to make my data access local.
All information comming from outside must be passed via parameter.
All procedures or functions I write, get the keyword EXPORT.
Even if today a procedure is only used once, I never know if I don't need
it tomorrow or next year in a different context.
All procedures are grouped into members depending on a common topic
and converted into service programs.
There are service programs that only contain Check-Procedures (i.e. for
Item-No.)
or that handle file access with native I/O etc.

In this way the final source code of a program will be very small, because
it only
consists of a bunch of procedure calls.

I think procedures and subroutines must coexist, but we have to use
more and more procedures instead of subroutines.

Birgitta


-----Ursprungliche Nachricht-----
Von: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]Im Auftrag von Joel Fritz
Gesendet: Freitag, 24. Juni 2005 19:02
An: RPG programming on the AS400 / iSeries
Betreff: RE: Assembly programmers do it a byte at a time



Seems to me subroutines have a role.  Because RPG has so many global
variables, there are times when a procedure that uses globals requires
the original programmer and anyone who modifies the code to pretend
their values can't be changed by adding a line of code to the procedure
that assigns a value directly. Passing by value can't defend against
this. There are some ways around this by using a service program or a
program call so the global is out of scope, but in a lot of cases it's
not worth the trouble.

Another feature of RPG that makes subroutines attractive is that file
names and record format names can't be represented by string variables
so truly generic file routines are impossible.

A third thing is that RPG data types except the integer, float, and
variable length character types have specific lengths.  (I know, int and
float types have length ranges.)  It's much easier to write a procedure
with arguments and return values that are more flexible than things like
packed 5,2 or char 8.  There are work arounds, but packed or signed
decimals work a lot better with money than anything else available.

Another factor, probably the root of it all, is that RPGIV has to be
backward compatible with the RPG Classic static memory model.

For small to medium programs I use subroutines for things that happen
only once like beginning of program housekeeping stuff or things that
modify a lot of global variables at once like a file write. I try to use
procedures for everything else.

I'm not saying you can't write a program that does everything with
procedures.  I believe that subroutines are sometimes a better tool for
the job.  They do provide functional decomposition and can be a
tremendous aid in making a program extensible if they're well designed
in the first place.  The don't hide data, but there's a lot of data
that's very hard to hide.

> -----Original Message-----
> From: rpg400-l-bounces@xxxxxxxxxxxx
> [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Alan Campin
> Sent: Thursday, June 23, 2005 4:45 PM
> To: rpg400-l@xxxxxxxxxxxx
> Subject: RE: Assembly programmers do it a byte at a time
>

>>>>>>>>>>>>>>>>>>>>>  Big Snip <<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>
> As far as subroutines being at some level of modularization,
> I see what you are saying but I am uncomfortable with the
> idea that subroutines are part of modularization. I still
> have to use them with embedded SQL rather than doing /Free
> and /End-Free all over the place but other than that,
> subroutines should be dead, dead, dead. They provide nothing
> that you really need to write good code. When we had nothing
> else in RPG III, that was what you had but did not let you do
> much of anything in software engineering. Makes me shudder to
> remember the days of trying to write good code in
> subroutines. Like living a long running nightmare.
> --
> This is the RPG programming on the AS400 / iSeries (RPG400-L)
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>
>

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