RE: RPG Indicators -- RPG400-L

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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