Re: Inheritance versus Generics

[Bertrand Meyer <bertrand@eiffel.com>]

Robert Dewar wrote (apropos my book "Object-Oriented Software
Construction", second edition, Prentice Hall, and some of its
critical comments about Ada 95):

> Well the world of language advocacy has always been one in which people
> are very ready to criticize without much practical experience. A good rule
> would be that you should not criticize a language unless you have written
> substantial amounts of real delivered production code in that language.

A bit facile perhaps. Prove that my comments about Ada 95 are wrong,
if they are; or, barring such a proof, state where and why you
disagree; but discuss my arguments, not the number of lines of
Ada 95 you assume I have compiled.

Large-scale practical experience with a language cannot hurt, of
course, but (posited) lack thereof does not disqualify one from
talking about the language. If we took Prof. Dewar's advice literally,
there would be (among other extreme consequences) no room for
broad-ranging programming language surveys, since no one can be
a seasoned programmer in all of - say - Ada, Eiffel, Lisp, Tcl,
Visual Basic, Fortran 90, Snobol etc. Or, to continue the reductio
ad absurdum, one of the justly praised aspects of the original Ada
design was that it was heavily critiqued before it was finalized 
Applying the Dewar principle would have meant that none of that
criticism was meaningful, since none of the critics had any
extensive practice in the languages being discussed (especially
those that were rejected, so that no one ever wrote any
"substantial amount of real delivered product code" in them!).

"You can't criticize Y because you have not written at least
x lines of working Y code" is not a valid dismissal. If you
want to debate someone's conclusions, you have to do it on
the merits or demerits of his stated case. Otherwise we would
fall into ad hominem disputes - and, as we all know, this is not
permitted to happen on Usenet.

Thanks, by the way, for the nice comments about the book.

-- 
Bertrand Meyer, President, ISE Inc., Santa Barbara (California)
805-685-1006, fax 805-685-6869, <Bertrand.Meyer@eiffel.com>
Web page: http://www.eiffel.com
OOSC-2 book info: http://www.eiffel.com/doc/oosc.html