Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!purdue!haven!mimsy!tank!eecae!cps3xx!usenet
From: usenet@cps3xx.UUCP (Usenet file owner)
Newsgroups: comp.lang.pascal
Subject: Re: Funny evaluation of functions
Summary: Programs depending on order of evaluation are erroneous
Message-ID: <4357@cps3xx.UUCP>
Date: 29 Aug 89 19:18:47 GMT
References: <20715@adm.BRL.MIL> <616@lehi3b15.csee.Lehigh.EDU>
Reply-To: rang@frith.egr.msu.edu (Anton Rang)
Organization: Engineering, Michigan State University, E. Lansing
Lines: 22

In article <616@lehi3b15.csee.Lehigh.EDU> edkay@lehi3b15.csee.Lehigh.EDU (Ed Kay) writes:
>
>    When I originally posed the question about the evaluation of: [ ...  ]
>
>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.

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--it isn't legal Pascal (though it may be
syntactically correct).  Ada explicitly distinguishes classes of errors
which the compiler MUST detect or MAY detect; dependence on order of
evaluation is an error, whether the compiler yells about it or not.

				Anton

+----------------------------------+------------------------+
| Anton Rang (grad student)	   | "UNIX: Just Say No!"   |
| Michigan State University	   | rang@cpswh.cps.msu.edu |
+----------------------------------+------------------------+