Re: Overloading in RPG.

["Peter Dow" <pcdow@xxxxxxxxx>]

Hi John, and John,

Looks like you still end up with the same amount of source code and no
indication in the name of what parameters are allowed. Wouldn't you really
want a prototype like

      DDaysDur          PR             5I 0  OPDESC
      D Date1                           *
      D Date2                           *

and hopefully have the operational descriptors tell you what type and size
of parameters were actually passed on a given call?

Peter Dow
Dow Software Services, Inc.
909 425-0194 voice
909 425-0196 fax



----- Original Message -----
From: "John Taylor" <john.taylor@telusplanet.net>
To: <RPG400-L@midrange.com>
Sent: Wednesday, May 09, 2001 6:33 PM
Subject: 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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