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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Ada Successor Language
Date: Tue, 26 Jun 2018 16:47:37 +0200
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Xref: reader02.eternal-september.org comp.lang.ada:53331
Date: 2018-06-26T16:47:37+02:00
List-Id: <comp.lang.ada>

On 2018-06-26 16:42, Dan'l Miller wrote:
> On Tuesday, June 26, 2018 at 9:17:02 AM UTC-5, Dmitry A. Kazakov wrote:
>> On 2018-06-26 15:59, Dan'l Miller wrote:
>>> On Tuesday, June 26, 2018 at 2:44:26 AM UTC-5, Dmitry A. Kazakov wrote:
>>>> On 2018-06-25 18:21, Dan'l Miller wrote:
>>>>> On Monday, June 25, 2018 at 10:19:15 AM UTC-5, Dmitry A. Kazakov wrote:
>>>>>> On 2018-06-25 16:44, J-P. Rosen wrote:
>>>>>>> Le 25/06/2018 à 16:21, Dmitry A. Kazakov a écrit :
>>>>>>
>>>>>>>> Ada could allow T'Class for untagged T. T'Class would be an indefinite
>>>>>>>> type with values consisting of the actual type's tag and its value. When
>>>>>>>> T is by-value type, you pass T'Class to a subprogram as tag + value.
>>>>>>>> When T is by-reference type, you pass tag + reference.
>>>>>>>>
>>>>>>>> Upon dispatch, you strip the tag from the value or reference before
>>>>>>>> passing value/reference down.
>>>>>>>
>>>>>>> It was a requirement of Ada95 that OOP be strictly contained, and that
>>>>>>> the same typing system as Ada83 be kept for those who don't want OOP.
>>>>>>
>>>>>> Don't want OO, don't declare T'Class objects. Where is a problem?
>>>>>
>>>>> The problem is that you just proposed 'Class for non-OO semantics.  Your proposal violates the Principal of Least Surprise.
>>>>
>>>> Remember, Ada is a strongly typed language, T'Class is not T, there is
>>>> no way it could break or change anything in T.
>>>
>>> Quit putting non sequitur words in my mouth.  I never said that it would break anything in T.  I said that it would break T'Class in •some• situations of the untagged extended records,
>>
>> Such situations are strictly non-existent for neither T'Class nor record
>> extensions are presently allowed for non-tagged types.
> 
> And yet, you propose them.

Proposing something that is already there would be kind of pointless...

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