RE: RPG Indicators -- RPG400-L

My own preference is also the DOW.

Not because of efficiency, or anything.  Only because its "one of my
standard patterns".  Meaning that this is my normal (as in done
thousands of times 'cause it works) way of doing it.

And whenever (and sometimes it does) it makes sense to use the DOU, I
use it.

Best tool for the job.

This whole DOW/DOU "war" is like the argument of box wrenches vs
open-end wrenches.  *Mostly* interchangeable, but sometimes you can only
use one or the other.


Bill Brosch
Swift Technologies

e-mail: bbrosch@stecnet.com
web site:       http://www.stecnet.com
phone:  1-847-289-8339
fax:            1-847-289-8939

-----Original Message-----
From: Rich Duzenbury [mailto:rduz@westernmidrange.com]
Sent: Saturday, April 15, 2000 11:06 PM
To: RPG400-L@midrange.com
Subject: RE: RPG Indicators


OH BOY.

I don't know why I'm responding to this one.  I think it's a religion
thing...but here's my .02 anyway.

I am a 'true believer' of doing the priming read, using the do-while
loop, and then reading just before the enddo.

Why do I think it's better?  The main reason is that there is one less
logical test inside the loop.  EOF is checked once and only once in each
iteration.  Also, the loop is never entered if there are no records.  I
can't think of any case where I've wanted to enter a loop via DOU in the
case where there aren't any records.

In my opinion, it's RPG that is forcing this issue on us.  If RPG were
to have the ability to do the read and test on the same line, we'd all
use DOW, I think with little question.  In C-ish languages, we would
write it thusly:

while (readfile('OURFILE')==TRUE)
  {
  ... do our processing...
  }

or perhaps
while (readfile('OURFILE'))
  {
  ... do our processing...
  }

Of course, the downside is that if you need to modify the read
statement, you have to do it twice.  The other rule of thumb I try to
stick to is to have read loops no longer than can comfortably be seen on
one SEU screen.  If I have more processing than can be done 'between the
reads', I typically move it into a subroutine.

<donning my flameproof gear>

Regards,
Rich


-----Original Message-----
From: owner-rpg400-l@midrange.com [mailto:owner-rpg400-l@midrange.com]On
Behalf Of Peter Dow
Sent: Saturday, April 15, 2000 9:43 PM
To: RPG400-L@midrange.com
Subject: Re: RPG Indicators


I agree Dan. This has the added advantage that using ITER makes sense,
although it also has the disadvantage that you have to repeat the
condition.
If there are more conditions than just eof, it could be modified
something
like this:

      c     Key           Setll     FileName
      c                   DoU       %EoF( FileName )
      c     Key           ReadE     FileName
      c                   If        %EoF( FileName ) or
      c                             (a = b and c = d) or
      c                             e = f
      c                   leave
      c                   EndIf
       ***   do stuff
      c                   EndDo


Peter Dow
Dow Software Services, Inc.
909 425-0194 voice
909 425-0196 fax

----- Original Message -----
From: Bale, Dan <DBale@lear.com>
To: <RPG400-L@midrange.com>
Sent: Friday, April 14, 2000 12:07 PM
Subject: RE: RPG Indicators


> My preference is to just have one file input operation for the loop,
i.e.:
>
>      c     Key           Setll     FileName
>      c                   DoU       %EoF( FileName )
>      c     Key           ReadE     FileName
>      c                   If        not %EoF( FileName )
>       ***   do stuff
>      c                   EndIf
>      c                   EndDo
>
> This has always worked for me.
>
> - Dan Bale

me: martin.mccallion@ukonline.co.uk
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