Path: utzoo!utgpu!water!watmath!clyde!rutgers!rochester!cornell!calvin!richard
From: richard@calvin.EE.CORNELL.EDU (Richard Brittain)
Newsgroups: comp.lang.fortran
Subject: Re: Forced variable declaration
Summary: REAL fortran programmers don't declare variables (unfortunately)
Message-ID: <190@calvin.EE.CORNELL.EDU>
Date: 28 Jan 88 09:26:45 GMT
References: <445@drilex.UUCP> <50500018@uxe.cso.uiuc.edu>
Organization: Cornell Space Plasma Physics, Ithaca, NY
Lines: 44

In article <50500018@uxe.cso.uiuc.edu>, mcdonald@uxe.cso.uiuc.edu writes:
> >I agree.  That's why it's a good idea for FORTRAN programmers  to include 
> >the line IMPLICIT LOGICAL (A-Z) or IMPLICIT CHARACTER (A-Z) in each main  
> >program and subprogram.  Even better, many compilers now make an 
> >IMPLICIT NONE available.  

> ... One of the original goals
> of Fortran was to eliminate the drudge work from progamming, and variable
> declaration is one of the worst.....

> ... The argument about mispelled variable names is a red
> herring that any REAL Fortran scientific programmer would recognize. An
> actual mistyped name is easily caught- it doesn't take any 6 hours..... 

I agree that implicit type declarations are a useful feature, and certainly
make for convenience on a "quick hack" and on large projects also.  However,
I think that "real" fortran programmers are all too often scientists first
and programmers second, and it really shows in the style, and hinders
understanding and modification later.  Granted, old fortran was
not an easy language in which to lay out structured, modular code, but
that hardly excuses some of the "spaghetti" code one often
finds in scientific programs (even code published as part of theses!).
	I write/use both "system" programs and "scientific" programs, using
fortran for both, and I find that my system code looks like C (almost
everything declared, very structured, very modular, and lower case).  After
learning (what I hope are) good programming skills, I became so aware
of bad practises in a lot of the old code that I work with, that now I simply
don't trust a lot of "working" code until I spend time checking it out.
I am spoiled by having a very friendly compiler to work with (allows many
structured extensions to f77, like while()...end while,  do...until(),       
loop(n)...end loop etc. (not a goto is sight) but still, even with vanilla
f77, I think it would make a big difference to the maintainance and
portability of scientific code if the authors learned good programming style.
   Fortran is still, and will always be my language of choice for numerical
work, (although I finally broke down and started learning C recently), but
I would love it if some of my scientist colleagues were better programmers.
   Two books on the subject which made a big difference to me are "The 
elements of programming style" and "Software Tools" both by Kernighan
and Plauger.  These have been around for a while but are still worth
mentioning.

          Richard Brittain,    Cornell Space Plasma Physics Group

 ARPA: richard@calvin.ee.cornell.edu