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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Ada Annoyances
Date: Tue, 19 Dec 2017 10:25:26 +0100
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Xref: reader02.eternal-september.org comp.lang.ada:49534
Date: 2017-12-19T10:25:26+01:00
List-Id: <comp.lang.ada>

On 2017-12-19 00:09, Randy Brukardt wrote:
> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message
> news:p169d9$6ka$1@gioia.aioe.org...

>> 1. You can derive a new type from a tagged type, which you cannot do from
>> a non-tagged type
> 
> I think you are using a non-Ada meaning of "derive" here, since an Ada
> derived type works for all types.

Yes, a common-sense "derive" (:-))

>> 2. You can clone a non-tagged type, which you cannot do with a tagged
>> type.
> 
> No idea what this means. You certainly can use a null extension on a tagged
> type, and that operates pretty much the same as a non-tagged type.

I mean:

    type X is new Integer;

which is very different from

    type X is new Integer with null record;

if the latter ever existed.

Cloning for tagged types is only possible when the type is wrapped into 
a generic:

    generic
    package Clone_Factory is
       type Y is tagged ...;
    end Clone_Factory;

    package Clone_1 is new Clone_Factory;
    package Clone_2 is new Clone_Factory;
    ...

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