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From: ok@goanna.cs.rmit.edu.au (Richard A. O'Keefe)
Subject: Re: Safety-critical development in Ada and Eiffel
Date: 1997/08/26
Message-ID: <5tu8se$433$1@goanna.cs.rmit.edu.au>#1/1
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References: <5siqrr$3of@jupiter.milkyway.org>
 <5smgts$p68$1@miranda.gmrc.gecm.com> <33EFCCE4.4CE0@flash.net>
 <5sq3fh$frg@wdl1.wdl.lmco.com> <dewar.871993443@merv>
Organization: Comp Sci, RMIT University, Melbourne, Australia.
NNTP-Posting-User: ok
Newsgroups: comp.object,comp.software-eng,comp.lang.ada,comp.lang.eiffel
Date: 1997-08-26T00:00:00+00:00
List-Id: <comp.lang.ada>


dewar@merv.cs.nyu.edu (Robert Dewar) writes:
>What should be the post condition after outputting an error message
>from a compiler?

>pragma Assert (programmer now understands what they did wrong);

>You need a *really* clever language to test that one (well I suppose the
>assertion routine executed at runtime could ask the programmer whether
>he understood :-)

That won't do as a postcondition for error messages.
One of my all-time favourite error messages came from the Burroughs
ESPOL compiler:

    "If you know what it means, implement it."

Such a message does not imply that the programmer did anything wrong at all.
(Although it _usually_ meant that.)

-- 
Four policemen playing jazz on an up escalator in the railway station.
Richard A. O'Keefe; http://www.cs.rmit.edu.au/%7Eok; RMIT Comp.Sci.