From owner-sc22wg5@open-std.org Thu Jan 29 11:58:45 2009 Return-Path: X-Original-To: sc22wg5-dom7 Delivered-To: sc22wg5-dom7@www2.open-std.org Received: by www2.open-std.org (Postfix, from userid 521) id 0E95AC56D24; Thu, 29 Jan 2009 11:58:45 +0100 (CET) X-Original-To: sc22wg5@open-std.org Delivered-To: sc22wg5@open-std.org X-Greylist: delayed 2309 seconds by postgrey-1.18 at www2.open-std.org; Thu, 29 Jan 2009 11:58:44 CET Received: from nougat.ucs.ed.ac.uk (nougat.ucs.ed.ac.uk [129.215.13.205]) by www2.open-std.org (Postfix) with ESMTP id 92F79C56CFF for ; Thu, 29 Jan 2009 11:58:43 +0100 (CET) Received: from holyrood.ed.ac.uk (holyrood.ed.ac.uk [129.215.16.14]) by nougat.ucs.ed.ac.uk (8.13.8/8.13.4) with ESMTP id n0TAKBVT007999 for ; Thu, 29 Jan 2009 10:20:13 GMT Received: from holyrood.ed.ac.uk (localhost [127.0.0.1]) by holyrood.ed.ac.uk (8.13.7/8.12.8) with ESMTP id n0TAKBeo014962 for ; Thu, 29 Jan 2009 10:20:11 GMT Received: (from dtm@localhost) by holyrood.ed.ac.uk (8.13.7/8.12.9/Submit) id n0TAKBKh014960 for sc22wg5@open-std.org; Thu, 29 Jan 2009 10:20:11 GMT Message-Id: <200901291020.n0TAKBKh014960@holyrood.ed.ac.uk> Date: 29 Jan 2009 10:20:11 GMT From: D Muxworthy Subject: Fwd: BOUNCE sc22wg5@open-std.org: Non-member submission from ["Craig Dedo" ] To: sc22wg5@open-std.org X-Edinburgh-Scanned: at nougat.ucs.ed.ac.uk with MIMEDefang 2.60, Sophie, Sophos Anti-Virus, Clam AntiVirus Content-Type: text/plain MIME-Version: 1.0 Content-Disposition: inline X-Scanned-By: MIMEDefang 2.60 on 129.215.13.205 Sender: owner-sc22wg5@open-std.org Precedence: bulk >From craig@ctdedo.com Thu Jan 29 01:54:48 2009 Return-Path: X-Original-To: sc22wg5@open-std.org Delivered-To: sc22wg5@open-std.org X-Greylist: delayed 399 seconds by postgrey-1.18 at www2.open- std.org; Thu, 29 Jan 2009 01:54:47 CET Received: from ws6-9.us4.outblaze.com (ws6-9.us4.outblaze.com [205.158.62.53]) by www2.open-std.org (Postfix) with SMTP id F102BC178D6 for ; Thu, 29 Jan 2009 01:54:47 +0100 (CET) Received: (qmail 20677 invoked from network); 29 Jan 2009 00:48:05 -0000 Received: from unknown (HELO Elessar) (craig@ctdedo.com@70.94.16.117) by ws6-9.us4.outblaze.com with SMTP; 29 Jan 2009 00:48:05 -0000 From: "Craig Dedo" To: "WG5 Mailing List" References: <20090128214406.86E15C178D6@www2.open-std.org> <20090128235744.C7EAEC178D6@www2.open-std.org> In-Reply-To: <20090128235744.C7EAEC178D6@www2.open-std.org> Subject: RE: (j3.2006) (SC22WG5.3931) Two requirements for critical software at JPL Date: Wed, 28 Jan 2009 18:47:56 -0600 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: AcmBpD+xOUaNVKh5RBWeuMT90ffCdgABGO7w Content-Language: en-us Disposition-Notification-To: "Craig Dedo" Everyone: I believe that asserts as part of the base language would be very useful and highly desirable. There are two ways I can think of right away to be able to turn them on or off at will. 1. Use CoCo or another pre-processor. 2. Use some kind of prefix in front of the assert that could be interpreted as a comment and then turn the assert on or off using a compiler option. Perhaps J3 and WG5 could standardize a prefix that would be used for all ISO-defined optional statements. FWIW, I believe that a good choice would be "!ISO", for "International Standards Organization", for a number of reasons. 1. I believe that this prefix is not used by any Fortran processor or pre-processor. 2. It is along the lines of other prefixes defined by existing Fortran compilers and also by third-party products such as HPF. 3. If a Fortran compiler has not yet been updated to include the ISO-defined optional statements, !ISO statements will appear as comments and be safely ignored. Thus, the use of !ISO for a prefix will not break existing programs. I strongly suspect that it is way too late in the development process of Fortran 2008 to include it in the current draft. Would J3 and WG5 be willing to pursue this idea as a TR? What other development options are there? What do others think of this idea? Sincerely, Craig Dedo 17130 W. Burleigh Place P. O. Box 423 Voice Phone: (262) 783-5869 Brookfield, WI 53008-0423 Fax Phone: (262) 783-5928 USA Mobile Phone: (414) 412-5869 E-mail: or > -----Original Message----- > From: j3-bounces@j3-fortran.org [mailto:j3-bounces@j3-fortran.org] On > Behalf Of Bill Long > Sent: Wednesday, January 28, 2009 18:01 > To: Van.Snyder@jpl.nasa.gov; fortran standards email list for J3 > Cc: sc22wg5 > Subject: (j3.2006) (SC22WG5.3931) Two requirements for critical > software at JPL > > > > Van Snyder wrote: >> I have just gotten a document frou the JPL Laboratory for Reliable >> Software, specifying coding requirements and recommendations to > increase >> the reliability of critical software in C. Most of these are to >> work >> around defects in C, but two (which are requirements, not >> recommendations) are germane to Fortran development: >> >> 1. Declare data objects at smallest possible level of scope. >> >> We've added the BLOCK construct. The facility it provides to >> encapsulate declarations in a region smaller than a scoping unit > would >> more likely be used if a specification part were allowed in every >> , not just a BLOCK construct. >> >> 2. Use static and dynamic assertions as sanity checks. >> >> These were on the J3 list in 2005, but didn't make it to WG5. >> >> One of the justifications for this requirement was a study reported > in >> http://research.microsoft.com/apps/pubs/default.aspx?id=70290 >> ("Assessing the relationship between software assertions and code >> quality"). The abstract remarks "... with an increase in the > assertion >> density in a file there is a statistically significant decrease in > fault >> density. Further, the usage of software assertions in these > components >> found a large percentage of the faults in the bug database." >> >> > > But then the "Lessons Learned" conclusion to the paper remarks "We > believe enforcing the use of assertions would not work well." > > We have recently added features to Fortran that we now have to > document > with comments along the lines of "this feature is supported by the > compiler because it is in the language spec, but we strongly > recommend > that it not be used in actual codes" because of disastrous > performance > implications. I hesitate to add more such features. > > I would note that our compiler (as a C program itself) contains an > enormous number of asserts. They help in pinpointing bugs closer to > the > point where something went wrong (as opposed to much farther down the > execution sequence when the consequences of the bug manifest as a > fatal > error). As such they are useful. We also get complaints that the > compiler is slow. For a compiler that's not horribly serious. For > production Fortran code poor performance is a non-starter. Different > environments and different objectives. At a minimum, if we wanted > asserts in Fortran, there would have to be a simple way to make them > appear to be comments to the compiler. (Basically the old "D" > lines.) > > Cheers, > Bill > > > -- > Bill Long longb@cray.com > Fortran Technical Support & voice: 651-605-9024 > Bioinformatics Software Development fax: 651-605-9142 > Cray Inc., 1340 Mendota Heights Rd., Mendota Heights, MN, 55120 > > > > _______________________________________________ > J3 mailing list > J3@j3-fortran.org > http://j3-fortran.org/mailman/listinfo/j3 -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.