Re: Structured RPG ?

[Hans Boldt <boldt@xxxxxxxxxx>]

John Carr wrote:
>Curious, Which one of these is more readable??
>Whats everyones opinion?
>
>-----------------------------------------
> Amt_Due  IFGT 0
> Payment  ANDGT 0
> Chk_Amt  ANDGT 0
>   EXSR Do_Payment
>
>   Endif
>   Endif
>   Endif
>
>or this
>--------------------------------------------------
>
>   IF ((Amt_Due >0) + (Payment >0) +
>     (Chk_Amt >0))
>
>   EXSR Do_Payment
>   Endif
>
>With writing it one of these ways,  Not only
>do you know that something will be done if these
>three conditions are true,  BUT you also know
>this is most likely dealing with money and
>something to do with payments.
>
>These add tremendous leveraging power to the
>Maintenance/Enhancement capability of your staff
>as well as the application base.  Things won't
>break as often from a mis-diagnosis of the
>problem and have the fix break more than the fix.
>
>Just Curious.  Which of the 4,  people like better?

Hi John!  While I don't think anyone here would
argue against what you're saying, I'd like to take
your example one step further (at the risk of being
picky).  Here's what I'd prefer:
--------------------------------------------------
C                   IF            Amt_Due > 0
C                             AND Payment > 0
C                             AND Chk_Amt > 0
C                   CALLP     Do_Payment (Transaction:
C                                Amt_Due: Payment:
C                                Chk_Amt)
C                   ENDIF
--------------------------------------------------
1st, the code as originally written won't compile.

2nd, I know the rationale for explicitly specifying
(unnecessary (redundant)) parentheses, but in most
cases, IMHO, it doesn't really add much value.  I
remember when Pascal was the "in" thing.  Pascal's
precedence rules meant that you always had to code
parentheses for any condition with more than one
sub-expression.  But languages like C and RPG have
more sensible precedence rules which mean that an
expression can be coded naturally without parens in
most situations.

3rd, using parameterized procedures has to be
preferable to old-style subroutines.

Cheers!  Hans

Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com
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