RE: Overloading in RPG.

[Scott Mildenberger <Smildenber@xxxxxxxxxxxx>]

Albert, 

Using your example below, why should every program that needs to use DaysDur
have to worry about converting to a common format.  It is just extra code
that every calling program needs that can be eliminated.

Think about the '+' operator in RPG (or any language for that matter).  It
is performing different 'procedures' depending on the data types it is
working on.  It could be additon or concatenation, and if it is addition the
operation will be different for differnt numeric types.  Just imagine that
if you wanted to add two numbers you had to convert your data to a 'common'
numeric type before/after actually performing the addition.

As far as simplifying maintenance, if I was implementing this I would have
one subprogram that did the actual calculations and all the others would
just be shell's that did the format conversions and called the subprogram
that did the real work.  At least in my mind, it would be nice that anytime
I wanted to calculate a duration in days I just call DaysDur and pass my
dates, no worrrying about how the date has to be formatted and doing that
conversion.

I do think overloading can be really useful in some cases, and of course
like any tool it can be abused.


Scott Mildenberger

> -----Original Message-----
> From: York, Albert [mailto:albert.york@nissan-usa.com]
> Sent: Thursday, May 10, 2001 12:20 PM
> To: 'RPG400-L@midrange.com'
> Subject: RE: Overloading in RPG.
> 
> 
> I still don't see any benefit to overloading. It seems like 
> an opportunity
> for confusion.
> 
> I don't see how you have simplified maintenance any. You still have 4
> subprograms to maintain. 
> 
> In addition, I don't see how there would be any guarantee that these
> routines would do the same thing, just because they have the 
> same name. As I
> understand it, they are entirely different.
> 
> I would prefer to have one procedure and do any necessary 
> conversion in the
> program. 
> 
> For example:
> 
>       DDaysDur          PR             5I 0
>            D CharDate1                      8A
>            D CharDate2                      8A
> 
>       C                   Eval      Cdate1 = Ndate1
>       C                   Eval      Days = DaysDur(Cdate1: Cdate2)
> 
> 
> Albert York   
> 
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