Re: Suggested Technique

[antoine.contal@xxxxxxx]

BTW, what is the free format equivalent to "do *hival"?

Regards.

--
Antoine CONTAL



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



Les informations contenues dans ce message sont confidentielles et peuvent 
constituer des informations privilegiees. Si vous n etes pas le destinataire de 
ce message, il vous est interdit de le copier, de le faire suivre, de le 
divulguer ou d en utiliser tout ou partie. Si vous avez recu ce message par 
erreur, merci de le supprimer de votre systeme, ainsi que toutes ses copies, et 
d en avertir immediatement l expediteur par message de retour.
Il est impossible de garantir que les communications par messagerie 
electronique arrivent en temps utile, sont securisees ou denuees de toute 
erreur ou virus. En consequence, l expediteur n accepte aucune responsabilite 
du fait des erreurs ou omissions qui pourraient en resulter.
--- ----------------------------------------------------- ---
The information contained in this e-mail is confidential. It may also be 
legally privileged. If you are not the addressee you may not copy, forward, 
disclose or use any part of it. If you have received this message in error, 
please delete it and all copies from your system and notify the sender 
immediately by return e-mail.
E-mail communications cannot be guaranteed to be timely secure, error or 
virus-free. The sender does not accept liability for any errors or omissions 
which arise as a result.
$!4$!