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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Amount of copying on returned constant objects
Date: Tue, 19 Jun 2007 16:33:26 -0500
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Date: 2007-06-19T16:33:26-05:00
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"Alex R. Mosteo" <devnull@mailinator.com> wrote in message
news:5dpp8pF35116bU1@mid.individual.net...
> Randy Brukardt wrote:
...
> > What really would help would be a way for the container to know when the
> > access was destroyed, but there isn't any obvious way to do that in Ada.
>
> I guess then that some reference counting companion type (or maybe making
> Cursors tagged and more heavyweight) was discarded because the distributed
> overhead?

Cursors can be tagged if the implementation so choses, but that doesn't have
an effect on the element access problem. For that you need something that
allows direct dereferencing, and in Ada as it stands, that can only be an
access type.

Having a companion type would work if it was impossible to separate the
access from the reference counter. But there is no way in Ada to have a
visible access type that cannot be assigned out of its surrounding wrapper.
(Which is why I said that Dmitry would say that redefinition of ".all" for a
private type could solve the problem.)

                       Randy.