Re: Good places to use "The Cycle" in today's RPG was->Re: FW:Niftiest thing(s) you have done in RPG ILE or /FREE -- RPG400-L

It's interesting the way this thread has morphed....

I never understood the appeal of a DOU loop for reading a file versus a
DOW loop.

Read File
Dow Not EOF
Process Stuff
Read File
Enddo

has always seemed much cleaner than

Dou EOF
Read File
If Not EOF
Iter
Endif
Process Stuff
Enddo

Why do you want to clutter up a simple Do loop with an explicit test that
gets done again implicitly when the Do loop does it's test? I have had
some argue that there was a measurable performance advantage to a single
Read statement versus 2 separate Read statements, but we're not writing
stuff for 32KB S/34's now.

Steve

Steven Morrison
Fidelity Express

"rick baird" <rick.baird@xxxxxxxxx>
Sent by: rpg400-l-bounces@xxxxxxxxxxxx
01/09/2009 02:12 PM
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RPG programming on the IBM i / System i <rpg400-l@xxxxxxxxxxxx>

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Subject
Re: Good places to use "The Cycle" in today's RPG was->Re: FW:Niftiest
thing(s) you have done in RPG ILE or /FREE

I never use endless loops, except for the example of screen processing
I posted earlier. In that case, and only in that case, it just makes
the code 'cleaner' imo.

the loop ends when the user asks it to (one of three different ways:
F3, F12 or successful data entry and update.) The rest of the time,
there are several points where the user asks the program to do
something and it returns to the screen (F4 prompt, enter to update,
but errors were found).

yes, they kinda look like gotos, but the structure is still there.
Iterate the loop or leave it, based on 5 different and unrelated
conditions.

It's better than coding the loop like this:

dow *inkd or (not errors and not *inkc and not *inkl)

Just thinking about how to write the above gave me a sharp pain just
behind my eyeball. no thanks.

On Fri, Jan 9, 2009 at 2:27 PM, Bryce Martin <BMartin@xxxxxxxxxxxx> wrote:

I still agree with the sentiment that writing an endless loop isn't as
maintainable. You are now doing 2 logic checks instead of 1. You have

do the check of whether 1=1 and then check if you are at the end of

file.

I know that you will never see the differenece when running a program

but

think of all the cpu cycles that are being wasted in the course of time

code written this way. If you have a popular ERP system that is made

of thousands of programs and everytime a file is read through you have
these extra logic steps you can quickly see how many cpu cycles will be
wasted by your package if you have thousands of customers. Everyday,

all

day, this stuff goes on. The numbers quickly become larger than what we
can count on our fingers and toes.

Maybe I'm too much of a purist, but I really don't like the current
programming mentality that, just because the machines are bigger now the
code doesn't need to be written as efficiently because no one will

really

notice. Its that kind of attitude that gives us things like Windows
Vista. Its pervasive, like it or not, and it eventually does show up
somewhere.

Thanks
Bryce Martin
Programmer/Analyst I
Ext. 4777

"Wintermute, Sharon" <Sharon.Wintermute@xxxxxxxxxxxxxxxx>
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01/09/2009 02:07 PM
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RPG programming on the IBM i / System i <rpg400-l@xxxxxxxxxxxx>

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Subject
RE: Good places to use "The Cycle" in today's RPG was->Re:
FW:Niftiest thing(s) you have done in RPG ILE or /FREE

Just have to chime in here.

One of my professors "dinged" us for primary reads. His reason? If you
have a do loop check it then. His style was

Dow 1= 1
Read
If %EOf
Leave
Endif
Process
Enddo

I still remember the ruler on my hands.

Sharon Wintermute

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Christen, Duane J.
Sent: Friday, January 09, 2009 12:59 PM
To: 'RPG programming on the IBM i / System i'
Subject: RE: Good places to use "The Cycle" in today's RPG was->Re:
FW:Niftiest thing(s) you have done in RPG ILE or /FREE

Your both wrong. :-)

Read file;

DoW Not %Eof(file);
// process data
Read file;
EndDo;

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Jeff Crosby
Sent: Friday, January 09, 2009 12:39 PM
To: 'RPG programming on the IBM i / System i'
Subject: RE: Good places to use "The Cycle" in today's RPG
was->Re: FW: Niftiest thing(s) you have done in RPG ILE or /FREE

I do it the way you don't.

dow '1';
read file;
if eof;
leave;
endif;
processdata;
enddo;

That's MY opinion and I'm sticking to it. <g>

--
Jeff Crosby
UniPro FoodService/Dilgard
P.O. Box 13369
Ft. Wayne, IN 46868-3369
260-422-7531
www.dilgardfoods.com

The opinions expressed are my own and not necessarily the
opinion of my company. Unless I say so.

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]

On

Behalf Of GUY_HENZA@xxxxxxxxxxxxxx
Sent: Friday, January 09, 2009 1:07 PM
To: RPG programming on the IBM i / System i
Subject: Re: Good places to use "The Cycle" in today's RPG

was->Re: FW:

Niftiest thing(s) you have done in RPG ILE or /FREE

Wow, just back from lunch and so many posts. I consider ITER and
LEAVE

to

be backwards from the way I think. I condition on what I

want to do

not

on

what I don't want to do.

dou eof;
read file;
if not eof;
processdata;
endif;
enddo;

This makes more sense to me than;

dou eof;
read file;
if eof;
leave;
endif;
processdata;
enddo;

That's my opinion and I'm sticking with it.

Regards,

Guy

Inactive hide details for "James Perkins"

<jrperkinsjr@xxxxxxxxx>"James

Perkins" <jrperkinsjr@xxxxxxxxx>

"James Perkins" To "RPG

programming on
the

<jrperkinsjr@xxxxxxxxx> IBM i /

System i"

Sent by:

<rpg400-l@xxxxxxxxxxxx>

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Subject Re:

Good places to use

01/09/2009 11:36 AM "The

Cycle" in today's

RPG was->Re: FW:

Niftiest

+---------------------------+

thing(s) you have done
in

| Please respond to | RPG ILE or /FREE
| RPG programming on the |
| IBM i / System i |
| <rpg400-l@xxxxxxxxxxxx> |
+---------------------------+

If you don't use ITER or LEAVE do you just have a giant IF
statement,

with

loads of nested IF's? I really can't see how you could

right a program

that
uses logic any other way, but then again just because I

can't think if

doesn't mean there is not a way.

James R. Perkins
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