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: 1108a1,9a0ff0bffdf63657 X-Google-Attributes: gid1108a1,public X-Google-Thread: f43e6,9a0ff0bffdf63657 X-Google-Attributes: gidf43e6,public X-Google-Thread: 103376,4b06f8f15f01a568 X-Google-Attributes: gid103376,public From: doylep@ecf.toronto.edu (Patrick Doyle) Subject: Re: Software landmines (loops) Date: 1998/09/07 Message-ID: #1/1 X-Deja-AN: 388605939 X-Nntp-Posting-Host: spark23.ecf Sender: news@ecf.toronto.edu (News Administrator) References: <35DBDD24.D003404D@calfp.co.uk> <35f1375e.6237208@news.erols.com> <35F074C9.E10C <35F2E907.594CD023@earthlink.net> Organization: University of Toronto, Engineering Computing Facility Newsgroups: comp.lang.eiffel,comp.object,comp.software-eng,comp.lang.ada Date: 1998-09-07T00:00:00+00:00 List-Id: In article <35F2E907.594CD023@earthlink.net>, Charles Hixson wrote: >Loryn Jenkins wrote: >> >> However, I think Meyer's approach to DBC is more powerful than this. >> Basically, Meyer's approach is to make the calling routine check the >> preconditions, not the called routine. > >But frequently the programmer does not have the choice of what language >is to be used. E.g., most of my work for the last couple of years has >been in various flavors of Visual Basic. (At least it's lots better >than Dartmouth Basic). Choice of language doesn't enter into it. A precondition is a condition that must hold for the effects of a routine to be well- defined. If that routine is called without the preconditions being satisfied, then you have a bug in your program. Thus, the caller must either check that the precondition holds, or else verify it by other means. -PD -- -- Patrick Doyle doylep@ecf.toronto.edu