Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.csd.uwm.edu!uakari.primate.wisc.edu!ames!sun-barr!newstop!sun!road!khb
From: khb@road.Sun.COM (Keith Bierman - Advanced Languages - Floating Point Group )
Newsgroups: comp.lang.fortran
Subject: Re: Two Fortran Standards
Message-ID: <124158@sun.Eng.Sun.COM>
Date: 5 Sep 89 17:27:25 GMT
References: <785hallidayd@yvax.byu.edu>
Sender: news@sun.Eng.Sun.COM
Reply-To: khb@sun.UUCP (Keith Bierman - Advanced Languages - Floating Point Group )
Organization: Sun Microsystems, Mountain View
Lines: 43

In article <785hallidayd@yvax.byu.edu> hallidayd@yvax.byu.edu writes:
>Hank Dietz (hankd@pur-ee.UUCP) in message (<12687@pur-ee.UUCP>) comments
>
>of a subset dialect (or, as appears the case now, a separate standard)?!?  Why
>is it not enough to retain _FULL_ backward compatibility with FORTRAN 77 (even
>with the archaic parts of that archaic language)?
>

My agreeing with Presley is a rare event ... but here goes.

It is possible for a program to operate (legally) on a f77 processor,
but operate differently (or fail) on a f88 processor. As Kurt pointed
out there are heuristics which work fairly well.

An example:

	Believe it or not, there are machines upon which

	          open(unit=50,file="oldfile")

	results in the file being positioned to the END OF FILE. 

	Since f77 did not define the file position after an open
	(oversight ? ). Nearly all implementations assume OPEN means
	position to start of data; as do nearly all codes.

	But there _probably_ are codes which EXPECT to be positioned
	at END OF FILE ...

	Under f88 the OPEN is defined to default to start of data,
	with the option of positioning at the end of data. 

I am fairly sure that any vendor who had the bizzare default
before, will allow that to be the default in f88 also (compiler
switch). 

The upshot is that language lawyers may not assert that all of '77 is
in '88 with the same interpretation ... 
	
Keith H. Bierman    |*My thoughts are my own. !! kbierman@sun.com
It's Not My Fault   |	MTS --Only my work belongs to Sun* 
I Voted for Bill &  | Advanced Languages/Floating Point Group            
Opus                | "When the going gets Weird .. the Weird turn PRO"