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From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: Puzzling question
Date: 1997/05/10
Message-ID: <dewar.863255522@merv>#1/1
X-Deja-AN: 240537677
References: <337209D7.4D25@aisf.com>
Organization: New York University
Newsgroups: comp.lang.ada
Date: 1997-05-10T00:00:00+00:00
List-Id: <comp.lang.ada>


Chris asks

    R (V => U.A'Address);  -- Why is this valid????????????????

why not? I can't see anything in the Ada 83 that suggests that this 
would be illegal. Address can be applied to objects, and U.A is an
object. Now note that often applying address to parameters can give
totally meaningless results, or at the best implementation dependent
results, but address is ID anyway, so this is not really an issue.

<<At work we are using Ada 83 and I thought that if a parameter is "out"
  in a procedure then only assignments could be made to the variable.
  In the call to R above, U.A would effectively be considered an input
  which I thought would be illegal since U is an "out" type.  I know that
  in Ada 95 this is ok, however, I don't know why this works under Ada 83.>>

Why is U.A'Address "effectively" considered as an input, nothing is
being read! Ada 83 and Ada 95 are identical here, the fact that in one
you could write U.A is totally irrelevant.