Re: Critique of Ariane 5 paper (finally!)

[Bertrand Meyer <Bertrand.Meyer@eiffel.com>]

Jon S Anthony wrote:
 
> There is nothing new about assertions or the notion behind
> [Design by Contract].  The basic ideas have been floated in
> various forms for a looonnggg time now.

If this is what the discussion finally amounts to, it is hard
to resist self-quoting from the second paragraph of the
preface to "Object-Oriented Software Construction"
(http://www.eiffel.com/doc/manuals/technology/oosc/preface):

 	just as inevitable is the well-known three-step sequence
	of reactions that meets the introduction of a new
	methodological principle: (1) "it's trivial"; (2) "it
	cannot work"; (3) "that's how I did it all along anyway".
	(The order may vary.)

I guess we have reached the third step now.

More seriously, it is absolutely correct that Design by
Contract is based on ideas that have been around for a long
time. It is also true that it includes original ideas too,
including some which in my experience shock most people
who encounter them for the first time, such as the
idea that to obtain more reliable software you should
usually *remove* checks. See also the connection with
inheritance (weakening/strengthening), the connection
with exceptions etc.

The question originality came up not long ago on comp.lang.eiffel;
Geoff Eldridge has collected at

http://www.progsoc.uts.edu.au/~geldridg/eiffel/liberty/v1/n1/bm/bmdbc.html

two messages posted in response, one by James McKim and
one by me, which tried to ascertain what is new and what
comes from earlier work. Also, the final sections
of the chapters on Design by Contract and exceptions in
"Object-Oriented Software Construction" have detailed
bibliographical discussions of earlier publications on related
topics.	

-- 
Bertrand Meyer, President, ISE Inc.
ISE Building, 2nd floor, 270 Storke Road, Goleta CA 93117
805-685-1006, fax 805-685-6869, <Bertrand.Meyer@eiffel.com>
http://www.eiffel.com, with instructions for download
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