• Subject: Re: RPG400-L Digest V3 #207
  • From: boldt@xxxxxxxxxx
  • Date: Fri, 11 May 2001 13:06:15 -0400
  • Importance: Normal



Alistair wrote:
>Correct me if I'm wrong (Hans?) but doesn't method overloading (as opposed
>to operator overloading) require some fancy form of late binding. Now I am
>not a compiler expert but I'm almost certain that RPG does not do this
>special form of late binding. I know it does late binding of some
>description but is this enough.

What?  Another invitation to participate in this thread?

In the "pure" OO languages, the message sent to an object is usually
interpreted at run-time.  That is a form of "late binding".

But that's not the only way to implement "overloading".  Look at how
C++ handles it.  The function names are munged in a way that encodes
the types of arguments in the name.  (The same could potentially be
done for RPG procedures without any other OO support.)  In this way,
names are resolved at bind time.

Some systems, like SOM, allow you to choose when to resolve names.

BTW, there's really no difference between "method" overloading and
"operator" overloading.

>By the way I take issue with the statement
>that overloading is not part of OO. METHOD overloading is very much part
of
>polymorphism which is a key section of OO. Yes you could argue that the
>mechanics behind it are found in non OO languages but this misses the
point
>IMO.

I'm not sure there's any point to argue with here.  I suppose it's a
matter of definition.  I see "overloading" not as a "part" of OO, but
more of a "characteristic" of OO.  OO in its pure sense deals with
sending messages to objects.  Since you can send a "print" message (for
example) to any object, OO has this "overloading" characteristic.

I don't mean to criticize anyone in particular, but I think a lot of
people miss the point with OO.  Maybe this is an example of the
classic prescriptivist/descriptivist debate, but I (as a descriptivist)
see terms like "polymorphism" and "overloading" and "inheritance" as
characteristics of OO, and not as a "recipe" for OO.  OO can be learned
without ever having to memorize the meanings of those fancy 4 and 5
syllable words adopted by the computer science intelligentsia.  The
essence of OO can be summed up using common one syllable words like
"is" and "has".

Cheers!  Hans

Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com

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