Re: Critique of Ariane 5 paper (finally!)

["W. Wesley Groleau x4923" <wwgrol@pseserv3.fw.hac.com>]

> > what some people disagree with is the use of two definitions of
> > DBC by the same advocates.
> >
> > Def'n 1 - Associating specifications with software elements" and
> > related practices.
> > Def'n 2 - The Eiffel implementation of a subset of these practices.
> >
> > Now before anyone denies having used definition 2,  please explain
> > what definition of DBC satisfies the claim "only Eiffel directly
> > supports DBC"
> 
> This has been explained many times. One can to some degree
> apply the principles of Design by Contract in any language,
> but among commercially commercially available languages Eiffel
> is the only one to offer direct support for "associating
> specifications with software elements" as part of the software
> elements themselves, i.e. using language constructs --
> preconditions, postconditions, class invariants, loop invariants,
> loop variants.

I say again: If DBC is defined as "Associating specifications 
with software elements", then Eiffel indeed directly supports 
a SUBSET of DBC.  Ada directly supports another subset of DBC.
C++ (shudder) directly supports yet another subset of DBC.  And 
with a little extra work, the user of any of these languages can 
handle a larger subset.  But none of them can completely support 
the whole thing.  And the intersection of the subsets is not empty.

I keep seeing most of the Eiffel advocates and a few of the Ada
advocates arguing, "My language supports DBC; your language does 
not look like my language; therefore your language does not 
support DBC."  Yet when they post specific examples, the syntax 
differences cannot hide (from me at least) the obvious similarities.

> In other languages ... does not go as far, because
> the presence of the assertion constructs provides Eiffel
> users with major benefits such as:

[ a long list of things that ARE being done with Ada and other
  languages ]

[ followed by the claim that only Eiffel users do these things. ]

-- 
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    Wes Groleau, Hughes Defense Communications, Fort Wayne, IN USA
Senior Software Engineer - AFATDS                  Tool-smith Wanna-be
                    wwgrol AT pseserv3.fw.hac.com

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