Re: Preventing Unchecked_Deallocation?

[AdaMagica <christ-usch.grein@t-online.de>]

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.  Ada 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.  If 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.  However, 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?rev=1.3
and http://www.adacore.com/2011/06/06/gem-107-preventing-deallocation-for-reference-counted-types/

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