Re: Suggested Technique -- RPG400-L

I see that, and understand and accept that.  Different minds function
different ways.  My own brain says to me "Booth, do you need a Leave because
your logic is messed up?" And, sadly, that is usually the case.   
 
---------------------------------
Booth Martin
http://www.martinvt.com
---------------------------------
-------Original Message-------
 
From: RPG programming on the AS400 / iSeries
Date: 01/31/05 15:23:26
To: RPG programming on the AS400 / iSeries
Subject: Re: Suggested Technique
 
The problem, Booth, is that some don't want to be bothered putting the F3
in a select or IF and then they have to worry about how to bypass the rest
of the code.  LEAVE takes care of that messiness for them.
 
Rob Berendt
--
Group Dekko Services, LLC
Dept 01.073
PO Box 2000
Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com
 
 
 
 
 
"Booth Martin" <booth@xxxxxxxxxxxx>
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01/31/2005 04:08 PM
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Subject
Re: Suggested Technique
 
 
 
 
 
 
While I understand the idea of DO *hival coupled with a leave, why not
just
say it in the first place, and have a DOU F3 and avoid the extra lines of
coding?  DOU F3 is pretty clear, too, isn't it?
 
 
 
---------------------------------
 
Booth Martin
 
http://www.martinvt.com
 
---------------------------------
 
-------Original Message-------
 
 
 
From: RPG programming on the AS400 / iSeries
 
Date: 01/31/05 15:03:41
 
To: rpg400-l@xxxxxxxxxxxx
 
Subject: Re: Suggested Technique
 
 
 
Hi Alan,
 
 
 
<snip>
 
There are some brilliant programmers here, however, who advocate avoiding
 
use of the "iter" and "leave" op-codes. I find it hard to avoid using them
 
myself, but am still open on that issue.
 
</snip>
 
 
 
Now there's a statement! :-)
 
 
 
I would be VERY interested to hear the reasons why LEAVE and ITER have
 
entered the "Hall of Shame" along with CABxx and GOTO.
 
 
 
Personally, I find them very useful and would need a very, very hard sell
to
 
convince me to stop using them. They do not preclude well structured code,
 
they have definite branching end-points, and they do not make code less
 
readable to a developer: All long-standing accusations levelled at CABxx
and
 
GOTO.
 
 
 
For example - a classic screen loop:
 
 
 
// Display screen...
 
do *hival
 
 
 
exfmt screen
 
 
 
// If user presses F3, leave screen loop...
 
if F3_pressed
 
leave
 
endif
 
 
 
// Validate user input...
 
validateInput()
 
 
 
// If user enters invalid data, re-display screen, displaying error
 
message...
 
if userEntersInvalidData
 
iter
 
endif
 
 
 
// If user elects to update current valid data, update and leave screen...
 
if F8_update
 
updateData()
 
leave
 
endif
 
 
 
enddo
 
 
 
 
 
For me this code is simple - you can only leave the screen if you press F3
 
or update valid data. How do I know??? There's only two ways to leave the
 
screen - via the two LEAVE op-codes. If the code goes beyond the enddo
then
 
F3 or F8 MUST have been pressed. In the case of F8, valid data MUST have
 
been entered. If the user enters invalid data then I force a re-display of
 
the screen (ITER) before any update code is reached - this forms a nice
code
 
buffer, beyond which I am assured that the input data is valid.
 
 
 
I also prefer using "do *hival" because I do not want any "implicit" exits
 
of the loop. I want to see the exit strategy EXPLICITLY coded within the
 
screen loop. My time is more precious than the CPU cycle time. If I can
 
read/modify the code faster because there are large marker flags in front
of
 
me then my company saves money. It's the old adage - KISS!
 
 
 
Just my preference.
 
 
 
Cheers
 
 
 
Larry Ducie
 
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