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For example,
Processing a subfile....
DoU SflRead;
ReadC Sfl1;
If %Eof;
SflRead=*On;
Leave;
EndIf;
// * Perform User Selection
Select;
// * Display Key Field Information
When Sel='1';
ExSR KeySR;
// * Display Field Information
When Sel='2';
ExSR FldSR;
// * Display Member Information
When Sel='3';
ExSR MbrSR;
// * Display Object Information
When Sel='4';
ExSR ObjectSR;
// * Display Database Relations
When Sel='5';
ExSR DBRSR;
// * Display Trigger Information
When Sel='6';
ExSR TrgSR;
// * Invalid Selection
Other;
EndSl;
// * Clear The Option Field
Sel=' ';
Update Sfl1;
EndDo;
For each When block I still want to "reset" the Sel field to blanks in the
SFL why repeat those 2 lines of code on each block???
Thanks,
Tommy Holden
HCA phone: 1-800-828-2561
direct line: 615-344-2151
fax: 1-866-593-0404
-----Original Message-----
From: Booth Martin [mailto:booth@xxxxxxxxxxxx]
Sent: Monday, January 31, 2005 3:46 PM
To: RPG programming on the AS400 / iSeries
Subject: RE: Suggested Technique
That is the sort of thing that sets my teeth itching. Would you have an
example of what code would always be done in every When block (excepting,
of course, the When F3 block which we know we are resolving with a Leave in
this scenario)?
I am asking this question because of my interest, not in an effort to be a
wise guy. It just is my experience that this sort of situation usually
means I've messed up the flow.
---------------------------------
Booth Martin
http://www.martinvt.com
---------------------------------
-------Original Message-------
From: RPG programming on the AS400 / iSeries
Date: 01/31/05 15:39:27
To: 'RPG programming on the AS400 / iSeries'
Subject: RE: Suggested Technique
<snip>
In my experience it
is almost always confusing to have additional code after the endsl, At that
point we have done whatever we intended to do and the subroutine really is
at a logical end.
</snip>
Unless the code after the endsl should be performed for EVERY "When
block"...why duplicate the code for every block???
Thanks,
Tommy Holden
-----Original Message-----
From: Booth Martin [mailto:booth@xxxxxxxxxxxx]
Sent: Monday, January 31, 2005 3:28 PM
To: RPG programming on the AS400 / iSeries
Subject: RE: Suggested Technique
I have no issue with Leave as an opcode and even use it from time to time.
I have noticed though that generally after the exfmt mentioned in our
example we almost always have a select loop with the command keys,
validation, and entry choices. Then we have an endsl. In my experience it
is almost always confusing to have additional code after the endsl, At that
point we have done whatever we intended to do and the subroutine really is
at a logical end.
In other words, it makes my teeth itch when I see code after the endsl, so I
would only rarely face the dilema you mention.
---------------------------------
Booth Martin
http://www.martinvt.com
---------------------------------
-------Original Message-------
From: RPG programming on the AS400 / iSeries
Date: 01/31/05 15:16:28
To: RPG programming on the AS400 / iSeries
Subject: RE: Suggested Technique
Because with DOU you will keep processing until the ENDDO. Why do all the
processing until the ENDDO when you can just LEAVE?
Michael Tobey
Applications Analyst
Foremost Farms USA
mike.tobey@xxxxxxxxxxxxxxxxx
IBM Certified AS/400 RPG IV Developer & RPG IV Programmer
-----Original Message-----
From: Booth Martin [mailto:booth@xxxxxxxxxxxx]
Sent: Monday, January 31, 2005 3:09 PM
To: RPG programming on the AS400 / iSeries
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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