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From: AdaMagica <christ-usch.grein@t-online.de>
Newsgroups: comp.lang.ada
Subject: Re: Preventing Unchecked_Deallocation?
Date: Mon, 6 Feb 2012 10:34:09 -0800 (PST)
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Date: 2012-02-06T10:34:09-08:00
List-Id: <comp.lang.ada>

On 6 Feb., 17:21, Adam Beneschan <a...@irvine.com> wrote:

> > When you say erroneous, do you mean forbidden by the language (i.e. an
> > exception) or that it will cause undefined operation?

Unpredictable behaviour (generally not an exception).

> I think the solution is not to expose the access type, but have your
> package define a private type. =A0Ada 2012 is supposed to have new
> mechanisms that allow packages to define "dereference" operations that
> could allow package users to use the same kind of syntax on objects of
> private types that they can use on access types. =A0If you do this, then
> it's likely that the package that defines the type can control what
> operations are available and not make Unchecked_Deallocation
> available. =A0However, I haven't yet studied the new feature so I can't
> say for sure.

See e.g. http://www.ada-auth.org/cgi-bin/cvsweb.cgi/ai05s/ai05-0268-1.txt?r=
ev=3D1.3
and http://www.adacore.com/2011/06/06/gem-107-preventing-deallocation-for-r=
eference-counted-types/

A further gem will eventually be published with more details about
implicit dereferencing and indexing.