Re: .NET approach

["Larry Loen" <lwloen@xxxxxxxxxx>]

>
> Full objects encapsulate data and member functions.  Using this
definition,
> the as400 provides half objects.
>
> Steve

Keep in mind that in the late '70s and early '80s, these were the only
objects being shipped in a practical, widely used system of any kind.  And,
were for several decades.

But, I'm not ready to conceed OS/400 has "half objects."  It certainly has
the properties you name, just harder to recognize.

OS/400 objects certainly "encapsulate" data generally.  A data base file is
an object.  Can you directly address its contents as if it were a user
space?

The main thing missing from our object strategy was inheritance.  This
obscures some of the object properties we do have.  When you have an API or
even a command that says "DLTPGM", you really have a member function, just
spelled awkwardly and with no inheritance.  DLTPGM does not work on a file
by mistake, for example.  If you had it in API form and passed it a system
pointer to a file object, it would say "wrong type".  That's as enforceable
as any C++ or Java member function.  Maybe more so.

Of course, that far back, even the LISP programmers hadn't invented
inheritance yet.  We certainly had and have encapsulation.  Moreover, we
have persistence in our objects and have had it for decades, something I
have not yet really seen in other object systems of any kind.  Java's
"serialize" function, for example, is a poor substitute.  It works, but it
isn't really a meaningful form of persistent object.

About the only "unencapsulated" objects I know of are user spaces.  It will
be interesting to see what .Net has that is really different than what we
already have or C++/Java already has.


Larry W. Loen  -   Senior Java and iSeries Performance Analyst
                          Dept HP4, Rochester MN


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