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Here would be a fine example of my point. This logic flow is just not very clear to me as a first-time viewer of the code. I'd bet that if you spent 30 minutes looking at what this code does and forced yourself to rewrite it without the Leave and all of the If/else/endif that you would reduce the lines of code by at least half and increase the clarity dramatically. --------------------------------- Booth Martin http://www.martinvt.com --------------------------------- -------Original Message------- From: RPG programming on the AS400 / iSeries Date: 01/31/05 16:11:10 To: 'RPG programming on the AS400 / iSeries' Subject: RE: Suggested Technique Booth; This is a display driver for a multi screen maintenance program: C DoU exit or C curScreen > maxScreen C If MSAG_match = *Off Surrogate Keys do C Eval sndPM_Msg_Id = 'PVM0094' not match. *MSAG data NOT current. No changes allowed. Press F8 in UPDATE mode to refresh. C Else C If editError C If screenChanged C Eval sndPM_Msg_Id = 'GEN0005' C Else C Eval sndPM_Msg_Id = 'GEN0407' C EndIf C Else C Eval sndPM_Msg_Id = 'EDI0046' C EndIf C EndIf /Include QRPGCBSRC,CQMHSNDPM C ExSr displayScreen /Include QRPGCBSRC,CQMHRMVPM C Select C When exit C Leave C When cancel F3 C If curScreen > 1 Back up one screen C Eval curScreen = curScreen - 1 if necessary. C Iter C Else C Leave C EndIf C When prompt F4 C ExSr promptField C ExSr editScreen C When refresh F5 C ExSr loadScreens C When manualSend = *On F7 C ExSr manuallySend C When refreshMSAG = *On F8 C ExSr archiveRecord C If archiveRtnCode >= 0 C ExSr defaultValues C Eval displayFields = PDDE911 C Eval fKeys = *ALL'0' C Eval protectRecord = *Off C Eval curScreen = curScreen - 1 Display same screen C ExSr processData C ExSr loadScreens C EndIf C When Not exit and Not cancel and C Not protectRecord and C Not prompt C ExSr editScreen C EndSl C If Not screenChanged and C Not editError and C fKeys = *ALL'0' C Eval curScreen = curScreen + 1 C EndIf C EndDo -----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 -- This is the RPG programming on the AS400 / iSeries (RPG400-L) mailing list To post a message email: RPG400-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/rpg400-l or email: RPG400-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/rpg400-l. .... -- This is the RPG programming on the AS400 / iSeries (RPG400-L) mailing list To post a message email: RPG400-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/rpg400-l or email: RPG400-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/rpg400-l. -- This is the RPG programming on the AS400 / iSeries (RPG400-L) mailing list To post a message email: RPG400-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/rpg400-l or email: RPG400-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/rpg400-l. ... -- This is the RPG programming on the AS400 / iSeries (RPG400-L) mailing list To post a message email: RPG400-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/rpg400-l or email: RPG400-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/rpg400-l. -- This is the RPG programming on the AS400 / iSeries (RPG400-L) mailing list To post a message email: RPG400-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/rpg400-l or email: RPG400-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/rpg400-l. .. -- This is the RPG programming on the AS400 / iSeries (RPG400-L) mailing list To post a message email: RPG400-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/rpg400-l or email: RPG400-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/rpg400-l. 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