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From: magnus@lglsun.epfl.ch (Magnus Kempe)
Newsgroups: comp.lang.ada
Subject: Re: Ichibah [sic] flames, and flames out over, Ada 9X
Message-ID: <1993Mar11.090445@lglsun.epfl.ch>
Date: 11 Mar 93 08:33:47 GMT
References: <1993Mar10.201515.6295@evb.com>
Organization: Ecole Polytechnique Federale de Lausanne
NNTP-Posting-Host: lglsun4.epfl.ch
Date: 1993-03-11T08:33:47+00:00
List-Id: <comp.lang.ada>

In article <1993Mar10.201515.6295@evb.com>, jgg@evb.com (John Goodsen) writes:
: If you don't make it easy for someone on the language search to see
: that Ada supports the concept of "class", then the acceptance of the
: language for OO development will not meet it's true potential.

In Ada 9X, you will be able to declare e.g. class-wide objects and
access types, such as:

	type Stack_Ref is
	  access Stack'class;
	
	A : Stack'class;

Is it easy enough to see that Ada 9X has "class" ?


: If the solution is to change the syntax from "tagged type" to
: "class" and leave it at that, then it doesn't sound like too
: much of a problem...

Contrary to OOP languages where objects per se are polymorphic,
Ada objects are monomorphic since Ada has by-value semantics.
Ada 9X programmers will _also_ be able to manage by-reference
semantics to have polymorphic references to objects, which is
what other OOP languages really provide.  Generally, a class
declaration in an OOPL implies that instances may belong to
the class itself or to a subclass, and that they are polymorphic;
in consequence, OOPLs rarely perform any significant amount of
strong, static type checking.

You don't want to throw away Ada's strong type system and static
checking, do you?

Anyway, I doubt that the adoption of Ada 9X will rest on the ability
of C++ programmers to grasp that "tagged" is somehow an equivalent of
their "class".  I don't think they will, since most C++ programmers
that I know enjoy C++ "because it's compatible with C".  Ada is
incompatible with C-oriented minds.  And that's a Good Thing.

If you want to learn of the many problems with C++, go read
  "C++?? A Critique of C++", Ian Joyner (e-mail: ian@syacus.acus.oz.au)
  "A Critique of the Inheritance Principle of C++", Markku Sakkinen,
  in Computing Systems, Vol. 5, No. 1, Winter 1992
  "The Darker Side of C++ Revisited", Markku Sakkinen,
  in Structured Programming (1992) 13: pp. 155-177.
(Warning: Referenceless flames and other hate-mail ignored on principle :-)

-- 
Magnus Kempe                "No nation was ever drunk when wine was cheap."
magnus@lglsun.epfl.ch                                   -- Thomas Jefferson