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=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,c4cb2c432feebd9d X-Google-Thread: 1094ba,c4cb2c432feebd9d X-Google-Thread: 101deb,15c6ed4b761968e6 X-Google-Attributes: gid103376,gid1094ba,gid101deb,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news2.google.com!news4.google.com!news3.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!wn12feed!worldnet.att.net!bgtnsc04-news.ops.worldnet.att.net.POSTED!53ab2750!not-for-mail From: "James Giles" Newsgroups: comp.lang.ada,comp.lang.fortran,comp.lang.pl1 References: <0ugu4e.4i7.ln@hunter.axlog.fr> <%P_cg.155733$eR6.26337@bgtnsc04-news.ops.worldnet.att.net> <6H9dg.10258$S7.9150@news-server.bigpond.net.au> <1hfv5wb.1x4ab1tbdzk7eN%nospam@see.signature> <2006052509454116807-gsande@worldnetattnet> Subject: Re: Ada vs Fortran for scientific applications X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1478 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1478 Message-ID: Date: Sun, 09 Jul 2006 21:36:07 GMT NNTP-Posting-Host: 12.72.113.35 X-Complaints-To: abuse@worldnet.att.net X-Trace: bgtnsc04-news.ops.worldnet.att.net 1152480967 12.72.113.35 (Sun, 09 Jul 2006 21:36:07 GMT) NNTP-Posting-Date: Sun, 09 Jul 2006 21:36:07 GMT Organization: AT&T Worldnet Xref: g2news2.google.com comp.lang.ada:5583 comp.lang.fortran:11858 comp.lang.pl1:1960 Date: 2006-07-09T21:36:07+00:00 List-Id: adaworks@sbcglobal.net wrote: > "Gordon Sande" wrote in message > news:2006052509454116807-gsande@worldnetattnet... >> >> How many Ada systems can match the undefined variable checking of the >> old WatFor or the current Salford CheckMate or the Lahey/Fujitsu >> global checking? It seems to be a thing associated with places that >> run student cafteria computing on mainframes. Not much used anymore. >> There was a similar student checkout PL/I from Cornell if I recall >> correctly. >> > The default for Ada is to do thorough range checking on all numeric > types. A designer may suppress that default, selectively, if it is > deemed unnecessary. > [... lots of Ada features ...] All the stuff I elided is interesting. Many of the features are even good things for languages to have. None of them were checks for undefined variables. Given the Ada program fragment: COUNT, SUM : INTEGER; [... lots of code ...] [... some paths through which assign to SUM ...] [... and some don't ...] COUNT := SUM+1; -- is SUM defined here or not? In most Ada implementations, as for most other languages, all the bit patterns in the representation of an INTEGER data type are valid integer values. There is no bit pattern representing NOI (Not An Integer) corresponding to the IEEE float idea of a NAN. Determining whether a variable is defined or not is a complex problem. It's made worse by the fact that the user can make the error message go away (though not usually the problem) by initializing the variable in the declaration. -- J. Giles "I conclude that there are two ways of constructing a software design: One way is to make it so simple that there are obviously no deficiencies and the other way is to make it so complicated that there are no obvious deficiencies." -- C. A. R. Hoare