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From: rnews@qut.edu.au
Newsgroups: comp.lang.eiffel
Subject: Re: RE: Exceptions and Assertions
Message-ID: <14932.26ecec80@qut.edu.au>
Date: 11 Sep 90 13:54:08 GMT
References: <1990Sep7.032121.6456@bony1.uucp>
Organization: Queensland University of Technology
Lines: 31


 
> In his reply, Bertrand Meyer asks:
> 
>>Should we tend towards a situation where precondition checking
>>will always be on, even in a released software product?
> 
> Yes! Yes! Yes! A million times yes! Let's use those MEGA-MIPS for
> something useful. I don't believe we can ever write software that is
> error free, we can at least write software that detects errors before
> doing too much damage. Hardware detects errors, why not software?

From the theoretical view point I agree that we should always test
preconditions (and preferably postconditions and all assertions).
From the practioners view point I disagree.  Software is getting
ever more complex (not including assertion testing already) and
there is a ever growing need for faster hardware to allow software
to execute at an usable speed.  As running Eiffel programs with
full assertion testing shows, assertion testing is a very heavy
overhead, and is unacceptable in most commercial applications.
Always testing assertions at runtime can only be done when we have
an efficient method of checking assertions (having a separate processor
and process for testing pre/post conditions would be an interesting
project.

Au revoir,

@~~Richard Thomas  aka. The AppleByter  --  The Misplaced Canadian~~~~~~~~~~~@
{ InterNet: R_Thomas@qut.edu.au           ACSNet:  richard@earth.qitcs.oz.au }
{ PSI:      PSI%505272223015::R_Thomas                                       }
@~~~~~School of Computing Science - Queensland University of Technology~~~~~~@