RE: Qualified sub-procedures

["Bartell, Aaron L. (TC)" <ALBartell@xxxxxxxxxxxxxx>]

I see where you are coming from and I agree that this would work, it would
just be more coding.  It would operate similar to how descriptors work with
the IFS and socket API's.  There are still a lot of things this model
wouldn't allow for, but it still does open up a lot of doors for an
instantiation concept.

Thanks for your comments Barb,
Aaron Bartell

-----Original Message-----
From: Barbara Morris [mailto:bmorris@ca.ibm.com]
Sent: Tuesday, October 01, 2002 9:57 AM
To: rpg400-l@midrange.com
Subject: Re: Qualified sub-procedures


"Bartell, Aaron L. (TC)" wrote:
> ...
> I'll agree that it kinda works in RPG, but not necessarily a good job.
What
> if I want to have multiple instantiations of the same object in my
program?

I had multiple instantiations of the same object in my sample.

>
> D addr1        s       TYPE(ADDRESS)
> D addr2        s       TYPE(ADDRESS)
>
> addr1.setCity("Denver")
> addr1.setState("CO")
> ...
> addr2.setCity("Chicago")
> addr2.setState("IL")
>
> and then let's say I want to pass that address into my tax calculation
> routine. . .
>
> tax = calcTax(35.12:addr1)
>
> Now calcTax will have my addr1 object and all of its functions (getCity,
> getState, etc).  You can emulate this with data structures, sort of,
except
> you don't get the functions of the object.
>

setCity (addr1 : 'Denver')
setState (addr1 : 'CO')
setCity (addr2 : 'Chicago')
setState (addr2 : 'IL')
tax = calcTax (35.12 : addr1)

Now calcTax will have your addr1 object and all of its functions.  If
you want each "object" to have a different set of functions, your
ADDRESS module needs to have procedure pointers in the ADDRESS data
structure, and the setCity etc procedures would call through to the real
procedure.  Sure, it's a bit more work on the procedure-writing side
than using a true OO language, but it's just as easy on the user's side.

difference between your version and my version is only a small syntactic
difference, "obj.fn(parm)" vs "fn(obj:parm)".

Barbara


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