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Newsgroups: comp.lang.ada
Date: Tue, 26 Jun 2018 06:59:16 -0700 (PDT)
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Subject: Re: Ada Successor Language
From: "Dan'l Miller" <optikos@verizon.net>
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Xref: reader02.eternal-september.org comp.lang.ada:53327
Date: 2018-06-26T06:59:16-07:00
List-Id: <comp.lang.ada>

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 =C3=A0 16:21, Dmitry A. Kazakov a =C3=A9crit=C2=A0:
> >>
> >>>> Ada could allow T'Class for untagged T. T'Class would be an indefini=
te
> >>>> 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 tha=
t
> >>> 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?
> >=20
> > The problem is that you just proposed 'Class for non-OO semantics.  You=
r proposal violates the Principal of Least Surprise.
>=20
> Remember, Ada is a strongly typed language, T'Class is not T, there is=20
> no way it could break or change anything in T.

Quit putting non sequitur words in my mouth.  I never said that it would br=
eak anything in T.  I said that it would break T'Class in =E2=80=A2some=E2=
=80=A2 situations of the untagged extended records, analogous to ways that =
are known in C++ as slicing.  Ada community wants one of C++'s most-maligne=
d problems where the compiler sometimes picks the wrong strong typing?  Who=
 knew?!