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From: ogden@seal.cis.ohio-state.edu (William F Ogden)
Newsgroups: comp.lang.eiffel
Subject: Re: Reference Semantics
Message-ID: <1991Jun21.230806.16183@cis.ohio-state.edu>
Date: 21 Jun 91 23:08:06 GMT
References: <1991Jun11.223305.16439@m.cs.uiuc.edu> <133611@tut.cis.ohio-state.edu> <1991Jun20.003529.27557@syacus.acus.oz.au>
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In article <1991Jun20.003529.27557@syacus.acus.oz.au> ian@syacus.acus.oz.au (Ian Joyner) writes:

>> ... it still seems that an object which is the target of multiple references
>>is completely analogous to a label which is the target of multiple GoTo's.

>Bill, I agree with most of what you are saying, but I don't think this
>is the reason for considering gotos harmful. If it were then we would
>also ban routines being called from multiple places.

The distinction between labeled points in a program and side-effect free
procedures is that any call to a procedure has the same fixed, and
comparatively simple effect, which includes returning control to the point
of invocation, whereas the effect of a goto to a particular label depends
heavily upon the locations of other goto's to that same label. It's an
issue of simplicity of semantics and of separation of concerns.

I suppose (by dangerous analogy) that if the multiple references to an
object couldn't be used to change its value, then references would be
perfectly safe too.