RE: DOU/DOW for READ Loops (My final word)

["Denis Robitaille" <DRobitaille@xxxxxxxxxxxx>]

Is'nt that funny how everybody knows all the pros and cons and that nobody want 
to replay all the arguments, but we always do? (myself included). 

A lot can be said for or against DOW and DOU. I think that whatever the choice, 
you should try to stick with just one of the 2. I understand that for contract 
programmer, this may not be an option.

Personnaly, my preference if for something that does not exist in RPG. I call 
it the generalized loop. I first saw this in the LISP language.

It would look like this in RPG:

c            loopB                                  * loop begin
c  key    chain    file            55          * some code
c            loopT           *in55 = *off     * loop test
c            eval .....                              * some code
c            loopE                                  * loop end

This structure combines both DOW and DOU.

 If there is code between loopB and loopT, you have a DOU. 

 If there is code between loopT and loopE, you have a DOW.

And best of all, you can have code before AND after the test that control the 
looping.

I would love to see something like that in RPG. It would make both DOW and DOU 
obselete.

Denis Robitaille
Directeur services techniques
Cascades Inc
819 363 5187
fax 819 363 5177


>>> <Mike.Barton@ecsoft.co.uk> 04/20/00 01:18pm >>>


Just to add my 2 pennies worth, I prefer the DOW construct.

One advantage is that it effectively has a 'first cycle processing'
section which can easily be inserted:

     Key         ChainFile                  80
      *in80       Ifeq *off
     { first clycle processing in here }
                  Endif

     *in80       DowEq*Off
      { main processing here }
      Key         Reade File                      80
                  Enddo


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