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From: hrubin@pop.stat.purdue.edu (Herman Rubin)
Newsgroups: comp.lang.fortran
Subject: Re: Cheating on the types
Summary: One of the problems with HLLs
Message-ID: <8421@mentor.cc.purdue.edu>
Date: 21 Mar 91 15:54:56 GMT
References: <1991Mar20.195732.15376@appmag.com> <10146@exodus.Eng.Sun.COM>
Sender: news@mentor.cc.purdue.edu
Lines: 40

In article <10146@exodus.Eng.Sun.COM>, wsb@boise.Eng.Sun.COM (Walt Brainerd) writes:
> In article <1991Mar20.195732.15376@appmag.com>, pa@appmag.com (Pierre Asselin) writes:
> > This simplified fragment violates the standard by passing reals to a
> > routine that expects integers.
 
> >       real rin, rout
> >       call icopy(rin, rout)
 
>         . . .
> >       subroutine icopy(iin, iout)
> >       integer iin, iout
 
> > Seems fairly innocuous, though.  Q:  are there implementations
> > where it would fail ?
 
 
> Yes.
 
> The Burroughs linkers on their old large systems B6700-B7900, etc.
> used to catch this.  I don't know what they do now about such
> things, but I think the trend is to do more checking of this
> sort along with global oprimization, so I would not recommend
> doing this (or anything else nonstandard) unless you really
> need to.

I have, using Fortran, deliberately set up subroutines which 
"cheated" on types.  How else would one read multiple precision
reals in or out?  I do not consider converting them to decimal
for output, or reading in decimal input, as reasonable; I wanted
to be sure that the numbers were exactly the machine numbers, and
I see no good reason to do unnecessary conversions.

There are also cases in which I have deliberately done boolean 
operations on "real" numbers.  The language designer, etc., who
does not allow someone to deliberately cheat on the types is doing
a great disservice to computing.
--
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399
Phone: (317)494-6054
hrubin@l.cc.purdue.edu (Internet, bitnet)   {purdue,pur-ee}!l.cc!hrubin(UUCP)