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From: Adam Beneschan <adam@irvine.com>
Newsgroups: comp.lang.ada
Subject: Re: Operation can be dispatching in only one type
Date: Thu, 19 Nov 2009 07:57:41 -0800 (PST)
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On Nov 18, 6:11=A0pm, Robert A Duff <bobd...@shell01.TheWorld.com>
wrote:

> My objection to run-time accessibility checks is that you can't pin the
> blame on a particular line of code:
>
> =A0 =A0 procedure P (X : access T);
>
> P either stores the access value in a long-lived global data structure
> (in which case P(Local'Access) is a bad idea in clients)
> or P does not do that
> (in which case P(Local'Access) is just fine).
> The author of P knows which one is the case,
> but has no way (other than comments) to communicate this to
> the author of the client.
> I've never seen a case where P decides at run time which it is.

Since I'm too lazy to look, I'm hoping you know this off the top of
your head: is there anything in the AI's about preconditions that
would allow something to be caught when P is called rather than later
in the body of P?  I thought there were also some proposed attributes
that could test accessibility levels.

                                  -- Adam