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From: cweir@richsun.UUCP (Charles Weir)
Newsgroups: comp.software-eng
Subject: Re: The Errors of TEX
Keywords: testing debugging structured-programming OOD
Message-ID: <624@richsun.UUCP>
Date: 19 Oct 89 00:56:50 GMT
References: <2402@munnari.oz.au>
Reply-To: cweir@richsun.UUCP (Charles Weir)
Organization: RICH Inc. , Franklin Park,IL
Lines: 33

In article <2402@munnari.oz.au> sharam@munnari.oz.au (Sharam Hekmatpour) writes:
>
>A number of people have commented about D. Knuth's "The Errors of TEX".
> [...] Therefore
>   I could wait until the whole program was written, before trying to debug any
>   of it. This saved a lot of time, because I did not have to prepare 'dummy'
>   versions of non-existent modules while testing modules that were already
>   written. I could test everything in its final environment..."
>	-- D. Knuth, The Errors of TEX, Software P&E, Vol 19(7).
>
>This is the worst testing technique I have ever heard of.
> [....]  That's why I'm so much against it. 
> It invariably leads to rewriting everything from scratch.

Yes, and why?

Part of the problem is just our own human limitations.   It is possible
to keep us to 9 (nine) things in our minds at one time.   A
well-designed module with a limited number of interfaces will have of
this order of things (interfaces, globals, whatever) to think about and
match and test.   So we can cope with modules.

A big bang - everything at once - debug session needs the engineer to
keep dozens, if not thousands of things in mind at once.

Impossible.

So it doesn't work.


Charles Weir

Own Opinions...