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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Call by reference vs. call by value
Date: 1996/07/21
Message-ID: <DuwxnG.F2E@world.std.com>#1/1
X-Deja-AN: 169345876
references: <31F10E50.726@egr.uri.edu>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: comp.lang.ada
Date: 1996-07-21T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <31F10E50.726@egr.uri.edu>,
Christopher Felaco  <felaco@egr.uri.edu> wrote:
>My reasons for posting this are twofold.  The first reason is to verify
>that this is correct, ...

It is.

>... and see if anyone else has been bitten by this
>particular undefined behavior.

Yes, they have.

>...  The second reason is to express some
>disappointment.

I agree.  Making this implementation dependent is bad language design,
IMHO.

However, your suggested solution -- to always pass 'in' parameters by
reference -- is unacceptable from an efficiency point of view.  It means
you would have to copy huge amounts of data around when passing arrays
from one procedure to another to another to another.

It seems to me that a language can be designed so as to avoid the
problem you are complaining about, while still retaining the desirable
efficiency.  But it wouldn't be Ada.

- Bob