From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: fac41,9a0ff0bffdf63657
X-Google-Attributes: gidfac41,public
X-Google-Thread: f43e6,9a0ff0bffdf63657
X-Google-Attributes: gidf43e6,public
X-Google-Thread: 1108a1,9a0ff0bffdf63657
X-Google-Attributes: gid1108a1,public
X-Google-Thread: 103376,4b06f8f15f01a568
X-Google-Attributes: gid103376,public
From: ahussey@it.uq.edu.au (Andrew Hussey)
Subject: Re: Software landmines (loops)
Date: 1998/08/31
Message-ID: <904556531.666222@miso.it.uq.edu.au>#1/1
X-Deja-AN: 386383142
Cache-Post-Path: miso.it.uq.edu.au!ahussey@isa.it.uq.edu.au
References: <slrn6sopmg.4fg.jdege@jdege.visi.com>
 <rfzpddz3s2.fsf@bnp-eng.remcomp.com>
 <902934874.2099.0.nnrp-10.c246a717@news.demon.co.uk> <dewar.903074236@merv>
 <6r1glm$bvh$1@nnrp1.dejanews.com> <dewar.903281994@merv>
 <6r9f8h$jtm$1@nnrp1.dejanews.com> <6renh8$ga7$1@nnrp1.dejanews.com>
 <6rf59b$2ud$1@nnrp1.dejanews.com> <l5HC1.6840$wN.1856764@news.giganews.com>
 <6rfra4$rul$1@nnrp1.dejanews.com> <35DBDD24.D003404D@calfp.co.uk>
 <m3ogt3qgca.fsf@mheaney.ni.net> <6sbuod$fra$1@hirame.wwa.com>
 <35f51e53.48044143@ <m3af4mq7f4.fsf@mheaney.ni.net>
Organization: Department of Computer Science and Electrical Engineering,
 The University of Queensland
X-Cache: nntpcache 2.3.3b3 (see http://www.nntpcache.org/)
Newsgroups: comp.lang.eiffel,comp.object,comp.software-eng,comp.lang.ada
Date: 1998-08-31T00:00:00+00:00
List-Id: <comp.lang.ada>

In <m3af4mq7f4.fsf@mheaney.ni.net> Matthew Heaney <matthew_heaney@acm.org> writes:

>I can almost live that.  The real problem, however, is that using an
>extra flag to terminate VASTLY complicates the predicate.  In fact, the
>flag doubles the number of states I have to think about when mentally
>evaluating the predicate!  That's the real source of the loop
>termination errors.

>(I shouldn't have to remind anyone, but just in case: George Miller did
>a famous study about human cognitive limits, and found that people can
>remember about 7 things, plus or minus 2.  That's why complex predicates
>make a programmer's head spin, and why he often gets loop termination
>wrong.)

>Using an exit from the middle avoids the headaches (literally)
>engendered by using an extra flag in the predicate.  When you want to
>exit, you just say that you want to exit, directly.  No mental
>gymnastics are required in order to determine whether you'll "really"
>exit, as would be the case using the flag approach.

That's brilliant, now your code is much easier to write!
Now let's see who has an easier time *testing* their code.
I think you'll find the control-flow errors you introduce
in the spaghetti you produce will more than make up for
any gain you have from rapid coding.  

A.