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From: Dmitry A. Kazakov <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: issue with implementing a visitor design pattern
Date: Mon, 26 Jan 2004 09:34:28 +0100
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On 24 Jan 2004 16:44:02 -0500, Robert A Duff
<bobduff@shell01.TheWorld.com> wrote:

>Dale Stanbrough <MrNoSpam@bigpoop.net.au> writes:
>
>> Robert A Duff wrote:

>Adding "case on 'Tag" to Ada would not be trivial.  One would have to
>reconcile the open-ended type extension capability of tagged types with
>the full-coverage rules of case statements.

Same as with integer types, an obligatory:

   when others =>
      ...

Then, of course, there could be subtypes of classes and thus finite
sets of tags:

type T is tagged ...;
type T1 is new T with ...;
type T2 is new T1 with ...;
...
type TN is new ...;

subtype Finite is T'Class (T1..TN);

Also useful would be dispatching on bare tags or an equivalent of
that.

--
Regards,
Dmitry A. Kazakov
www.dmitry-kazakov.de