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From: Simon Wright <simon@pogner.demon.co.uk>
Subject: Re: Help me to chose between ADA 95 and C++
Date: 1999/12/14
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Date: 1999-12-14T00:00:00+00:00
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Chris Powell <chris.powell@rrds.co.uk> writes:

> Did the coding standard for the safety-critical software developed allow
> full use of Ada 95 constructs? My experience of safety-critical software
> is that while Ada is usually the chosen language, most of the Ada
> language features are disallowed. I worked on one project where
> constrained types were not allowed (because they are more likely to
> raise exceptions than unconstrained types), no packages (because data
> hiding limited testability) and certainly nothing as difficult to test
> as inheritance/polymorphism could be used.

I can understand most of this, even if I don;t like it: indeed SPARK
Ada would probably not differ (speaking only as one who knows the name
of it): but not allowing constrained types! because they are "more
likely to raise exceptions than unconstrained types"!!!!! Isn't the
standard practice in SC software to PROVE that no exceptions will be
raised and THEN disable range checking? and wouldn't you expect it to
be easier to do the proof if you give the prover a helping hand by
using constrained types?