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From: Adam Beneschan <adam@irvine.com>
Newsgroups: comp.lang.ada
Subject: Re: Passing the same actual as both in and out formal parameters?
Date: Tue, 17 Nov 2009 16:23:56 -0800 (PST)
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On Nov 17, 4:11=A0pm, "Jeffrey R. Carter"
<spam.jrcarter....@spam.acm.org> wrote:
> Randy Brukardt wrote:
>
> > Right, that's my understanding of the point. The only problem is, there
> > isn't any sane way to describe such an assertion.
>
> Given that the types are by-reference, would comparing 'access of the par=
ameters
> =A0 serve?
>
> pragma Assert (A'access /=3D B'access);

First of all, for this to work in the general case, that would need a
major change in language semantics, since you need an access type in
order for 'Access to be allowed.  The only way this would be legal is
if there happened to be exactly one "=3D" operator directly visible with
operands of some named access-to-T type.  (Also, if "=3D" were
overridden with a user-defined operator that did something unexpected,
it would fail, but nobody would do that.)

Second, it only catches the case where the operands are of the same
type; it won't catch other overlaps such as

   P2 (A =3D> Object, B =3D> Object.Component);

                                     -- Adam