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From: jbuck@galileo.berkeley.edu (Joe Buck)
Newsgroups: comp.object,comp.lang.ada
Subject: Re: ada-c++ productivity
Message-ID: <11966@pasteur.Berkeley.EDU>
Date: 13 Mar 91 23:12:21 GMT
References: <1991Mar7.163106.29477@wdl1.wdl.loral.com> <1991Mar10.151220.2581@forwiss.uni-passau.de>
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Reply-To: jbuck@galileo.berkeley.edu (Joe Buck)
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In article <1991Mar10.151220.2581@forwiss.uni-passau.de>, wiese@forwiss.uni-passau.de (Joachim Wiese) writes:
|> C++ is a "better C" but not a full OO-language. C++ is an OO-language that
|>  offers a lot of flexibility. To much flexibility and to
|> much pointers (to much C) to lead to quality software and productivity.
|>  I would rather be interested in comparing a _real_ 
|>  "full OO-language" as  EIFFEL vs. ADA.

C++ and Eiffel are full object-oriented languages; Ada is not.  Some
definitions, from Grady Booch's "Object-Oriented Design With Applications",
which has been generally recognized in this group as one of the best texts
available:

"Object-oriented programming is a method of implementation in which programs
are organized as cooperative collections of objects, each of which represents
an instance of some class, and whose classes are all members of a hierarchy
of classes united via inheritance relationships."

He quotes Cardelli and Wegner's definition:

"A language is object-oriented if and only if it satisfies the following
requirements:

- It supports objects that are data abstractions with an interface of named
  operations and a hidden local state

- Objects have an associated type (class)

- Types (classes) may inherit attributes from supertypes (superclasses)"

Ada lacks attribute #3 and is therefore not an object-oriented language.
Languages that satisfy the first two clauses but not the third are called
by Cardelli and Wegner "object-based" languages; Ada is an object-based
language.  C++ satisfies all three attributes.

Eiffel certainly has some nice features lacking in C++, but then C++
has some nice features lacking in Eiffel.  And of course it is possible
to write bad programs in any language.


--
Joe Buck
jbuck@galileo.berkeley.edu	 {uunet,ucbvax}!galileo.berkeley.edu!jbuck