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: f43e6,9a0ff0bffdf63657 X-Google-Attributes: gidf43e6,public X-Google-Thread: fac41,9a0ff0bffdf63657 X-Google-Attributes: gidfac41,public X-Google-Thread: 103376,4b06f8f15f01a568 X-Google-Attributes: gid103376,public X-Google-Thread: 1108a1,9a0ff0bffdf63657 X-Google-Attributes: gid1108a1,public From: cwr@cts.com (Will Rose) Subject: Re: Software landmines (loops) Date: 1998/09/06 Message-ID: <905071271.568311@optional.cts.com>#1/1 X-Deja-AN: 388358640 Cache-Post-Path: optional.cts.com!cwr@crash-i2.cts.com References: <904556531.666222@miso.it.uq.edu.au> <6sgror$je8$3@news.indigo.ie> <6sh3qn$9p2$1@hirame.wwa.com> <6shbca$66c$1@news.indigo.ie> <6shhq7$lut$1@hirame.wwa.com> <6sjbso$1lk$2@news.indigo.ie> <6sjijg$36r$1@hirame.wwa.com> <6skhcm$1dr$2@news.indigo.ie> <6skqf3$ <35F0B5B0.8E2D0166@s054.aone.net.au> Organization: CTS Network Services (CTSNET), San Diego, CA Followup-To: comp.lang.eiffel,comp.object,comp.software-eng,comp.lang.ada Newsgroups: comp.lang.eiffel,comp.object,comp.software-eng,comp.lang.ada Date: 1998-09-06T00:00:00+00:00 List-Id: Loryn Jenkins (loryn@s054.aone.net.au) wrote: : Ell wrote: : > : > Loryn Jenkins wrote: : > : > >> Then clearly you have not read much of Dijkstra. The citation you want is : > >> the citation I have given you many many times. Go look it up Elliott. : > : > >Yes, look it up. Read it. Acknowledge that that is what Dijkstra was : > >saying. : > : > How can I acknowledge that, if I haven't seen it? And you all can't : > point to that stuff on flowcharting as some kind of proof that the : > founders of SP said we should adhere to se/se. : > : > >Remember, you *may* disagree with him. But it is silly not reading what : > >he actually said. : > : > That book is out of print and RCM knows it. : That's what libraries are for. : > If RCM had *any* shred of : > text to prove that they explicitly advocated se/se in structured : > coding he would quote it. : A charitable interpretation of what they have already quoted has : demonstrated that. : But leave that aside. Let us say that many people who have read the book : have made that interpretation. It is certainly possible for you to claim : that no, se/se is not what Dijkstra was going on about, he was really : using se/se as a tool to demonstrate that, say, code should be provable. : And it is the provability of code that is the foundation of structured : programming. : This may or may not be correct. But it is an acceptable line of : argument. : But an even better line of argument may in fact be, yes, Dijkstra does : believe in se/se. But what he should have been concentrating on was, : say, provability. : > : > > And it is fantasy arguing that he wasn't discussing : > >se/se. : > : > It's a deplorable attempt at deception for RCM to state that se/se is : > a cornerstone of SP without a shred of evidence. : How about, 'a cornerstone of SP as advocated by Dijkstra'. (That doesn't : necessarily mean he was right; that doesn't necessarily mean that it is : today, in fact, the basis for SP (as practised by the majority of : practitioners.) It merely means that he advocated it. (And, I think, it : would be incorrect to debate that his view has influenced many people. : That is, it is an historical fact that his views have influenced many : people (other than RCM ... take BM as an example) about the use of : se/se. : > : > It's fantastic gullibility to think RCM is right about se/se without a : > shred of evidence; : What evidence? A quotation? Hah. That's not proof that se/se is right. : That's only proof that it is an historical fact Dijkstra argued for : se/se. Whether se/se is right is another matter entirely. : > to believe him based on faith, because I'll bet : > dollars to doughnuts that you can't show me any proof either. : Like you, I don't have the book at hand. But RCM's claims of Dijkstra's : position seems 'right' to me (based on triangulating what I've read of : many other people who've read Dijkstra). I'm not sure which book started this discussion, but Dijkstra's "Notes on Structured Programming" in "Structured Programming", Dahl, Dijkstra and Hoare, say inter alia: When we now take the position that it is not only the programmer's task to produce a correct program but also to demonstrate its correctness in a convincing manner, then the above remarks [on program size and structure] have a profound influence on the programmer's activity; the object he has to produce must be usefully structured. The remaining part of this monograph will be mainly an exploration of what program structure can be used to good advantage. In what follows it will become apparent that program correctness is not my only concern, program adaptability or manageability will be another. This stress on program manageability is my deliberate choice, a choice that, therefore, I should like to justify. ...[description of flowcharts which] "share the property that they have a single entry at the top and single exit at the bottom"... ...Alternatively: restricting ourselves to the three mentioned types of decomposition leads to flowcharts of restricted topology compared with the flowcharts one can make when arrows can be drawn from one block leading to any other. Compared with that greater freedom, to restrict oneself to the clauses presents itself as a sequenceing discipline. Why do I propose to adhere to this sequencing discipline? The justfication for this decision can be presented in many ways... Will cwr@crash.cts.com