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From: Robert Dewar <robert_dewar@my-dejanews.com>
Subject: Re: Assertions
Date: 1999/05/21
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Date: 1999-05-21T00:00:00+00:00
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In article
<Pine.A41.3.96-heb-2.07.990520114314.161678A-100000@pluto.mscc.h
uji.ac.il>,
  Ehud Lamm <mslamm@mscc.huji.ac.il> wrote:
> Are there any documents about this design issue? I am very
> much interested in DBC ("design by contract"), which I think
> is one of the nicest ideas in
> SE. So why did Ada95 dismiss it?

DBC is a methodology, which of course you can adopt in any
language, and indeed Ada is quite well suited for this purpose.
The issue of whether specific language features should be
designed into the language to support DBC is a different
one. It is of COURSE not the case that all elements of a
DBC approach can be captured by Eiffel assert statements
(as soon as you constrain the syntax and semantics of such
assertions, you limit their applicability).

Obviously some level of support for design contracts seems
like a good idea. FOr example, an Ada package spec is exactly
an interface contract.

Are assertions a la Eiffel the right form?
Not clear the answer is yes.
There are MANY other similar constructions and a lot of
 design room here.

But to think that Ada dismissed DBC just because it did not
adopt the particular partial assertion language facilities
of Eiffel misses the point I think.


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