From DMV@salford-software.com Tue Apr 9 18:53:15 1996 Received: from relay-4.mail.demon.net (relay-4.mail.demon.net [158.152.1.108]) by dkuug.dk (8.6.12/8.6.12) with SMTP id SAA23345 for ; Tue, 9 Apr 1996 18:53:06 +0200 Received: from post.demon.co.uk ([158.152.1.72]) by relay-4.mail.demon.net id ao15223; 9 Apr 96 16:52 GMT Received: from salfsoft.demon.co.uk ([158.152.93.93]) by relay-3.mail.demon.net id aa00952; 9 Apr 96 12:07 +0100 From: David Vallance Organisation: Salford Software Ltd To: WG5 Mailing List Date: Tue, 9 Apr 1996 11:56:09 +0000 Message-ID: <7396.DMV@salford-software.com> Subject: Re: (SC22WG5.1057) Default Data Type - 2 Different Definitions? Reply-To: DMV@salford-software.com Priority: normal X-mailer: Pegasus Mail for Windows (v2.23) via wpkGate v2.01 As one who has implemented Fortran and provided user support in various ways over many years, I would agree that any ambiguity in a term or definition will lead to untold problems downstream. Perhaps a close look at the use of the term "default" in the context of other language and related standards would not go amiss? Dave > Date: Wed, 03 Apr 96 07:43:08 -0600 > From: Craig Dedo > Subject: (SC22WG5.1057) Default Data Type - 2 Different Definitions? > To: WG5 Mailing List > Dear Members of the WG5 Mailing List: > > Here is an item that I am throwing out for discussion. > > While thinking about the problem that Keith Bierman mentioned in his > January 29 e-mail titled "Fodder for Meeting" (x3j3.1996-37), I realized that > we may have a problem with the term "default". In using the concept of > "default" kind of data type, we MAY actually be using two differing and > incompatible definitions. > > 1. The "default" kind for a data type is the kind of the data type which > is the most frequent and suitable for the application which the programmer is > writing. > > 2. The "default" kind for a data type is the kind of data type which is > most natural for the hardware architecture which the Fortran compiler is > compiling source code for. > > These two definitions need not be the same. Many Fortran compilers offer > a compiler option which allows the user to choose the default kind of a data > type. The user usually chooses a kind type which occurs most frequently in > the application. However, this is not necessarily the kind which is most > natural for the hardware. > > For example, a user may encounter only a few large integers in the problem > but many small ones. Such a user would choose 2 byte integers as the default > integer kind. However, if the processor is 32 bits, it naturally processes > data 4 bytes at a time. The Fortran compiler for such a processor may > implicitly or explicitly consider 4 byte integers to be the default. Thus, > there is an incompatibility between what the user specifies and the Fortran > compiler assumes. > > I believe that the conflict in these two definitions is at the heart of > the problems that we experience when we specify that certain data objects in > Fortran should be of a default kind. Therefore, in our work on Fortran 2000, > we should clearly define both usages of the concept of default kind and > rigorously distinguish which one we are using in any given situation. > > What do others think? > > ---------- > Sincerely, > Craig T. Dedo Internet: Craig.Dedo@mixcom.com > Elmbrook Computer Services Voice Phone: (414) 783-5869 > 17130 W. Burleigh Place > Brookfield, WI 53005 Disclaimer: These opinions are mine alone. > USA They do NOT represent any organization. > > "They that can give up essential liberty to obtain a little temporary > safety deserve neither liberty nor safety." -- Benjamin Franklin (1759) > > > -- David M Vallance Managing Director Salford Software Ltd Tel: +44 (0) 161 834 2454 Adelphi House Fax: +44 (0) 161 834 2148 Adelphi Street WWW: http://www.salford.ac.uk/ssl/ss.html Salford, M3 6EN UK