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From: Matthew Heaney <matthew_heaney@acm.org>
Subject: Re: A question for my personal knowledge.
Date: 1999/05/15
Message-ID: <m3emkipkmk.fsf@mheaney.ni.net>#1/1
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NNTP-Posting-Date: Sat, 15 May 1999 05:40:08 PDT
Newsgroups: comp.lang.ada
Date: 1999-05-15T00:00:00+00:00
List-Id: <comp.lang.ada>

Florian Weimer <fw@cygnus.stuttgart.netsurf.de> writes:

> > Yes, that is even better. Now In Ada, how does one send a message to a 
> > tagged record?? 
> 
> `Message(Tagged_Record_Variable);'?
>
> I'm not sure whether Ada is a bit nearer to the message-based model
> than C++ or Java because I haven't understood all the implications of
> the Ada approach yet.

One implication of the Ada approach is that binary operations are more
natural:

  Marry (John, Jane);

The operation "marriage" applies to each object equally.

> C++ and Java lack truely dynamic message dispatching (i.e. you can
> only send a message to an object if its class (or some suitable base
> class) is known at compile-time), and judging from my preliminary
> understanding, Ada doesn't have this capability, either.  Of course,
> you can implement dynamic dispatching in almost any (even non-OO)
> languages used today, but without syntactic support of some kind, your
> code won't be easy to write or read.

Your choice of nomenclature is unfortunate, because everyone else uses
the term "dynamic message dispatching" to refer to run-time binding,
which Ada95, C++, and Java _do_ have.