Re: Suggested Technique

["Richard ECUYER" <recuyer@xxxxxxx>]

Dow 1 = 1 ;  //for example.

----- Original Message -----
From: <antoine.contal@xxxxxxx>
To: "RPG programming on the AS400 / iSeries" <rpg400-l@xxxxxxxxxxxx>
Sent: Tuesday, February 01, 2005 11:26 AM
Subject: Re: Suggested Technique


>
>
>
>
> 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
>
>
>
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