RE: Overloading in RPG.

John,

Like most features of a language, it's up to the programmer to use it
appropriately. Here is another example that might help ignite your
imagination:

Without overloading:


     DDaysDurC         PR             5I 0
     D CharDate1                      8A
     D CharDate2                      8A

     DDaysDurN         PR             5I 0
     D NumDate1                       8P 0
     D NumDate2                       8P 0

     DDaysDurCN        PR             5I 0
     D CharDate1                      8A
     D NumDate2                       8P 0

     DDaysDurNC        PR             5I 0
     D NumDate1                       8P 0
     D CharDate2                      8A


     C                   Eval      Days = DaysDurC(Cdate1: Cdate2)
     C                   Eval      Days = DaysDurN(Ndate1: Ndate2)
     C                   Eval      Days = DaysDurCN(Cdate: Ndate)
     C                   Eval      Days = DaysDurNC(Ndate: Cdate)


With overloading:

     DDaysDur          PR             5I 0
     D CharDate1                      8A
     D CharDate2                      8A

     DDaysDur          PR             5I 0
     D NumDate1                       8P 0
     D NumDate2                       8P 0

     DDaysDur          PR             5I 0
     D CharDate1                      8A
     D NumDate2                       8P 0

     DDaysDur          PR             5I 0
     D NumDate1                       8P 0
     D CharDate2                      8A


     C                   Eval      Days = DaysDur(Cdate1: Cdate2)
     C                   Eval      Days = DaysDur(Ndate1: Ndate2)
     C                   Eval      Days = DaysDur(Cdate: Ndate)
     C                   Eval      Days = DaysDur(Ndate: Cdate)


One function name to remember instead of 4, simpler code in the calling
procedure, and potentially fewer maintenance issues.


John Taylor
Canada


> -----Original Message-----
> From: owner-rpg400-l@midrange.com [mailto:owner-rpg400-l@midrange.com]On
> Behalf Of jpcarr@tredegar.com
> Sent: Wednesday, May 09, 2001 3:37 PM
> To: RPG400-L@midrange.com
> Subject: RE: Overloading in RPG.
>
>
>
> >The main idea behind overloading is that you can have same named sub
> >procedures with _different_ amounts of parms or _different_ parm types
> >passed to them.
>
>
>
> I know what you mean,  I am just saying that using the "Number of parms
> passed" as the method(haha) of telling you that this thing can do
> more than
> one thing,  I feel is dubous.
>
> It obscures what the thing does.
>
> >>EVAL      RC        =  OPEN(%ADDR(FILENAME): OFLAG)<<
>
> Opens the IFS file doing translation,
>
> >>EVAL      RC        =  OPEN(%ADDR(FILENAME): OFLAG: OMODE: CODEPAGE) <<
>
> Opens the IFS file with the right codepage, authority, etc(both depending
> on the flags set)
>
> It just seems stupid.    Explaining that "First I Open it with the right
> code page, and create, etc,  THEN
> OF COURSE I have to close it so that I can Open it again and tell it to do
> translation"
>
> I understand it,  It just seems a silly way of telling a function what you
> want to do by the NUMBER of parms passed.
> I can see the value of the "principle of overloading"   Again I
> implemented
> it in CL 15 years ago with one CL doing 15 functions passing it an
> externally defined D/S  with a Function Number being one of the
> subfields(ie 1- 15).
> Was it C++ or Java?  No, But it still used the "princple" of overloaded
> functions.
>
>
> Just an opinion nothing more Thats all,
>
> John
>
>

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