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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Equivalent of dynamic_cast (downcast) for tagged types
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Date: Fri, 28 Jan 2011 18:21:12 +0100
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Date: 2011-01-28T18:21:12+01:00
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On Fri, 28 Jan 2011 08:44:08 -0800 (PST), Adam Beneschan wrote:

> On Jan 28, 1:16�am, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
> wrote:

>> It must be overriding because Adjust is a primitive operation.
> 
> Wrong.

[information hiding rationale skipped]

Yes, it is wrong (language design). The operation is primitive even if
invisible in *some* contexts. It means that there might exist other
contexts where two operations would conflict. Furthermore, Ada designers
tried (and expectedly failed) to ensure that "multiple inheritance" always
override. This goal is inconsistent with the information hiding principle,
as you have just pointed out. Now, the can of worms is open and the worms
are crawling far and wide.

P.S. Some silly rules exist to alleviate the mess. Like the rule that an
interface cannot be implemented privately. That does not help. Multiple
inheritance issues must be addressed properly. There is no other way.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de