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=0.4 required=5.0 tests=BAYES_00,FREEMAIL_FROM, FREEMAIL_REPLY,FROM_STARTS_WITH_NUMS,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: 1108a1,9a0ff0bffdf63657 X-Google-Attributes: gid1108a1,public X-Google-Thread: 103376,4b06f8f15f01a568 X-Google-Attributes: gid103376,public X-Google-Thread: f43e6,9a0ff0bffdf63657 X-Google-Attributes: gidf43e6,public From: "John I. Moore, Jr." <70672.1744@compuserve.com> Subject: Re: Software landmines (loops) Date: 1998/10/03 Message-ID: <6v5en9$d46$1@winter.news.erols.com>#1/1 X-Deja-AN: 397364394 References: <6qfhri$gs7$1@nnrp1.dejanews.com> <35cb8058.645630787@news.ne.mediaone.net> <902934874.2099.0.nnrp-10.c246a717@news.demon.co.uk> <6r1glm$bvh$1@nnrp1.dejanews.com> <6r9f8h$jtm$1@nnrp1.dejanews.com> <6renh8$ga7$1@nnrp1.dejanews.com> <6rf59b$2ud$1@nnrp1.dejanews.com> <6rfra4$rul$1@nnrp1.dejanews.com> <35DBDD24.D003404D@calfp.co.uk> <6sbuod$fra$1@hirame.wwa.com> <35f51e53.48044143@news.erols.com> <6sdiav$e0g$1@hirame.wwa.com> <6sfcft$70p$1@hirame.wwa.com> <1dg8p3r.vfredh1aou58iN@n207167116191.inetworld.net> <6v2nr9$t8l$1@hirame.wwa.com> <6v39i0$fte$1@winter.news.erols.com> <6v4d5l$blb$1@hirame.wwa.com> X-MimeOLE: Produced By Microsoft MimeOLE V4.72.2120.0 X-Complaints-To: abuse@rcn.com X-Trace: winter.news.erols.com 907427369 13446 207.172.239.164 (3 Oct 1998 15:09:29 GMT) Newsgroups: comp.lang.eiffel,comp.object,comp.software-eng,comp.lang.ada Date: 1998-10-03T00:00:00+00:00 List-Id: Robert C. Martin wrote in message <6v4d5l$blb$1@hirame.wwa.com>... >Yes, Mills did make this definition. However, I am referring to the >work of Dijkstra in the late 60's and early 70's. Dijkstra was very >clear about the notion of single entry and single exit within the >body of a loop. I believe that Mills' do-while-do loop is an >unauthorized addition to Dijkstra's work. Two points: 1. Mills also wrote about structured programming in the 60's and 70's. He was a pioneer and champion of the ideas in the same sense as Dijkstra. 2. Mills construct of do-while-do has a single entry and single exit, as do all of the other structured programming constructs. Using an Ada-like syntax, consider the following: loop get x; exit when x satisfies some condition; process x; end loop; I contend that this logic is natural, that the loop has only a single entry and exit, and that it doesn't violate any of the structured programming guidelines. Of course, one can rewrite it by using a standard while-loop, just as one can rewrite any repeat-until loop using a while-loop, but in order to do so you must repeat some part of the logic outside of the loop. _____________________________________________________________ John I. Moore, Jr. SoftMoore Consulting 16233 Monty Court Rockville, MD 20853-1344 phone: (301) 924-0680 email: softmoore@compuserve.com