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  1.  Home
  2. RPG400-L
  3. August 2017

RE: This is cool.

I don't know how this is wallowing in the past. The capability to initialize the array in the data structure definition has been around a lot longer than free format as Jon demonstrated. Yet it is only now that someone says we need to do it this way, and if you don't agree with me, you are wallowing in the past. Fact is, this "pre-run time" initialization is not unique to RPG. Even Java as something similar with static class initialization methods, which are separate from the property declaration. Are folks who use that wallowing in the past?

Consider that

dcl-ds *N;
*N Char(7) Inz('CPF3C51');
*N Char(7) Inz('CPF3C52');
*N Char(7) Inz('CPF3C53');
*N Char(7) Inz('CPF3C54');
*N Char(7) Inz('CPF3C55');
OkList Char(7) Dim(5) Pos(1) Ascend;
end-ds;

If %Lookup(ErrorReturn.MessageId:OkList) > 0;

was offered as an improvement over

dcl-ds Messages;
Message1 Char(7) Inz('CPF3C51');
Message2 Char(7) Inz('CPF3C52');
Message3 Char(7) Inz('CPF3C53');
Message4 Char(7) Inz('CPF3C54');
Message5 Char(7) Inz('CPF3C55');
OkList Char(7) Dim(5) Pos(1) Ascend;
end-ds;

If %Lookup(ErrorReturn.MessageId:OkList) > 0;

because the latter is "too much work", but

dcl-s OkList Char(7) Dim(5) Ascend CTData;

if %Lookup(ErrorReturn.MessageId:OkList) > 0

**CtData OkList
CPF3C51
CPF3C52
CPF3C53
CPF3C54
CPF3C55

Which is even less work and ends up doing the same thing in a familiar way is somehow bad even though the same thing has been available since the time of fixed format RPG.

It all seems a bit arbitrary to me. Particularly since they all seem equally valid in my mind. I don't use GOTO...TAG, or CAB...TAG because there are better structured forms which aren't really equivalent. The comparison of CTData to using CAB is a bit specious though. The use of inline initialization vs. CTData is more simply a matter of how much you like to type. The only argument that gets close is Charles who wants the initialization with the definition, but even then it is not frequently close to where it is used. I actually like both methods. If the data is short and the array small, I am more likely to initialize it in-line. But if the data or array are long, I am more likely to use CTData, or a table, or a message file. Even though the last two require far more code.

Mark Murphy
Atlas Data Systems
mmurphy@xxxxxxxxxxxxxxx


-----Roger Harman <roger.harman@xxxxxxxxxxx> wrote: -----
To: "RPG programming on the IBM i (AS/400 and iSeries)" <rpg400-l@xxxxxxxxxxxx>
From: Roger Harman <roger.harman@xxxxxxxxxxx>
Date: 07/31/2017 11:28PM
Subject: RE: This is cool.


I was trying to think of a nice response but Alan nailed it. I hate dumbing things down for those who want to wallow in the past.

Roger Harman
COMMON Certified Application Developer - ILE RPG on IBM i on Power

-----Original Message-----
From: RPG400-L [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Alan Campin
Sent: Monday, July 31, 2017 3:48 PM
To: RPG programming on the IBM i (AS/400 and iSeries)
Subject: Re: This is cool.

<snip>
**CTData OkList
CPF3C51
CPF3C52
CPF3C53
CPF3C54
CPF3C55

A little more idiomatic for RPG (easier for an RPG programmer to understand
at a glance)
</snip>

But so is CAB for most RPG programmers. Doesn't mean I want to use it.

On Mon, Jul 31, 2017 at 11:27 AM, Mark Murphy/STAR BASE Consulting Inc. <
mmurphy@xxxxxxxxxxxxxxx> wrote:

Yes, but you don't need O specs to use compile time data. If you use the
initialized data structure, when does that get initialized/reclaimed? I
guess if you use it in a procedure, that would be each time the procedure
is called, and goes away when the procedure ends because it is in automatic
storage. Maybe a slight benefit if the procedure isn't called, not so much
if it is called multiple times. So I could see arguing against compile time
data in a service program, but not necessarily in a program. After all,
isn't:

dcl-s OkList Char(7) Dim(5) Ascend CTData;

If %Lookup(ErrorReturn.MessageId:OkList) > 0;

...

**CTData OkList
CPF3C51
CPF3C52
CPF3C53
CPF3C54
CPF3C55

A little more idiomatic for RPG (easier for an RPG programmer to
understand at a glance)






-----Alan Campin <alan0307d@xxxxxxxxx> wrote: -----
To: "RPG programming on the IBM i (AS/400 and iSeries)" <
rpg400-l@xxxxxxxxxxxx>
From: Alan Campin <alan0307d@xxxxxxxxx>
Date: 07/28/2017 09:38PM
Subject: Re: This is cool.


Are there even "O" specs anymore in 100% free and Main programs? I don't
think so and the problem with the old compile type arrays is that you are
talking static storage that gets initialized when the module starts and
stays there until the program or activation group ends.

On Fri, Jul 28, 2017 at 5:53 PM, Booth Martin <booth@xxxxxxxxxxxx> wrote:

If I am understanding it, this is essentially moving an array's data to
where the array is defined instead of following the "O" specs? Which is,
indeed, cool. Although I admit to also liking Jon/Sue's solution for
messages at the end of the article he linked earlier.



On 7/28/2017 6:38 PM, Nathan Andelin wrote:

The syntax may not be clear on first blush, but looks pretty slick once
you
understand it.


On Fri, Jul 28, 2017 at 12:03 PM, Alan Campin <alan0307d@xxxxxxxxx>
wrote:

dcl-ds *N;
*N Char(7) Inz('CPF3C51');
*N Char(7) Inz('CPF3C52');
*N Char(7) Inz('CPF3C53');
*N Char(7) Inz('CPF3C54');
*N Char(7) Inz('CPF3C55');
OkList Char(7) Dim(5) Pos(1) Ascend;
end-ds;


If %Lookup(ErrorReturn.MessageId:OkList) > 0;


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