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From: Robb.Nebbe@di.epfl.ch (Robb Nebbe)
Newsgroups: comp.lang.ada
Subject: Re: Type extension questions
Date: 22 Mar 1995 12:01:40 GMT
Organization: Ecole Polytechnique Federale de Lausanne
Sender: nebbe@lglsun3.epfl.ch (Robb Nebbe)
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Date: 1995-03-22T12:01:40+00:00
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In article <D5tFuE.1vx@ennews.eas.asu.edu>, koehnema@enuxsa.eas.asu.edu (Harry Koehnemann) writes:
|> I have a couple questions on Ada95 tagged types.  These appear to be
|> easy questions, but I can't seem to locate an answer for either.
|> LRM references would also be appreciated with an answer.
|> 
|> 1) Is it possible to derive a type such that the parent operations are not
|>    available to the user of the new type?  This question is equivalent to
|>    the ability to do private inheritance ala C++ - class B: private A { ...};
|>    I would assume the answer is yes, but haven't yet figured out how.

Yes. For example when you need a type to be controlled typically you don't
want to expose the finalize, initialize and adjust operations to the client
so you write:

	package P is

	    type T is private;

	private

	    type T is new Ada.Finalization.Controlled with ...

	    procedure Adjust( Object : in out T );

	    ...

	end P;

A private_type_declaration must be completed with a
full_type_declaration which is in 3.2.1

Robb Nebbe