Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!mentor.cc.purdue.edu!mace.cc.purdue.edu!ags
From: ags@mace.cc.purdue.edu (Dave Seaman)
Newsgroups: comp.lang.pascal
Subject: Re: Funny evaluation of functions
Message-ID: <3007@mace.cc.purdue.edu>
Date: 29 Aug 89 22:35:44 GMT
References: <20715@adm.BRL.MIL> <616@lehi3b15.csee.Lehigh.EDU> <4357@cps3xx.UUCP>
Reply-To: ags@mace.cc.purdue.edu (Dave Seaman)
Organization: Purdue University
Lines: 27

In article <4357@cps3xx.UUCP> rang@frith.egr.msu.edu (Anton Rang) writes:
>In article <616@lehi3b15.csee.Lehigh.EDU> edkay@lehi3b15.csee.Lehigh.EDU (Ed Kay) writes:
>>I was mildly surprised that result was 25 rather than 20, because
>>I thought that the evaluation of X might precede the evaluation of
>>ONE(X).  I should have more clearly stated that I was curious whether
>>the STANDARD had anything to say about the issue.

And I should have made it clearer when I posted my answer several days ago
that I was referring to the standard, which I had in front of me at the time.

I just assumed that when I said that "if the function 'one' has side
effects, then the result of x*one(x) is implementation-dependent", people
would know that I meant THE STANDARD SAYS that the result is
implementation-dependent.  What other basis could I possibly have had for
making the statement?  Certainly not by trying the program on different
compilers, which proves nothing.  The implementation could be wrong.

>I don't know whether the standard explicitly says so (not having my copy
>with me), but any program which depends on a particular order of
>evaluation is erroneous

Correct -- and the standard does explicitly say so, as I pointed out in my
previous posting.

-- 
Dave Seaman	  					
ags@seaman.cc.purdue.edu