Re: Qualified sub-procedures

[Barbara Morris <bmorris@xxxxxxxxxx>]

"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