Re: OO, C++, and something much better!

[jsa@alexandria (Jon S Anthony)]

In article <E4p4qH.4A@world.std.com> bobduff@world.std.com (Robert A Duff) writes:

> In article <E4oMBG.62@jvdsys.nextjk.stuyts.nl>,
> Jerry van Dijk <jerry@jvdsys.nextjk.stuyts.nl> wrote:
> >Smalltalk would not exactly be my first choice if I had to built a large
> >reliable system. Neither would Ada be my first choice for developing
> >a PC GUI front-end.
> 
> But suppose I want to build a large reliable system with a GUI front end?
> 
> >... But I have developed a banking application in which the
> >presentation- and application layers were written in Smalltalk, while
> >the functional- and interface layers were written in Ada.
> 
> OK, that's an OK answer, given the current state-of-the-art, but there
> are serious costs to interfacing between the two.  I claim that it's
> possible to design a programming language that supports both at the same
> time, without the interfacing difficulties.

Actually, that is more than an OK answer.  It is highly unlikely that
a single "theory" (pgmlan in this context) can encompass and express
all possible view points on a particular subject and maintain any kind
of coherency itself.  I'd go further and say it is out right ludicrous
to make such a claim.  It has never been done - not even in things
that actually _are_ sciences and engineering (forget about software
and computer "science") - and there is no evidence whatsoever that it
_can_ be, let alone _will_ be.  The idea of "one language for all
things" is every bit as silly as "_the_ theory of everything".

So, it makes a lot of sense to concentrate on working out explicit
well defined interface points between PL semantics where the
"impedance mismatch" is controlled and "easily" managed.  Of course
this would require real communication and cooperation between the
various camps - wow, what a novel idea...

Notice that something like CORBA is not really the same thing (it
functions a bit more like Ontalingua in the KE/KA field).  It tries to
solve this problem by being a kind of "universal common denominator"
for describing interfaces with a lot of automated assistance in
translating between it and various targets.  While it does work (even
between ST and C), and basically is better than anything else
currently available, something like Ada's _Interfaces_ subsystem for
each language would have far less "semantic impedance mismatch"
problems.


> Interfacing between two different languages is a serious problem.  The
> design of Ada 95 goes to a great deal of trouble to make interfacing
> between Ada and C (etc) as easy as possible, but it's still painful.

Agreed, but it is pretty trivial compared to the next task up the
ladder: that of having a module's contextual semantics spelled out and
codified as part of its overall semantic description, thereby allowing
at least the possibility of true parts catalogues.  Don't hold your
breath...


> So I don't buy the idea that you can just choose whatever language is
> best for each module, and then paste them together.

Then the software biz is never going to get beyond the artisan or
blacksmith stage it's been stuck in for the last 35 odd years.


/Jon
-- 
Jon Anthony
Organon Motives, Inc.
Belmont, MA 02178
617.484.3383
jsa@organon.com