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From: "Vladimir Olensky" <vladimir_olensky@yahoo.com>
Subject: tagged types extensions - language design question
Date: 2000/01/27
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Newsgroups: comp.lang.ada
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Date: 2000-01-27T00:00:00+00:00
List-Id: <comp.lang.ada>

The question is :

   Why in Ada it is  not allowed to extend both public
 and private part of the tagged type at one step ( using
 kind of syntax as in the following example ):

package P is

   type T is tagged private;

   type T1 is new T with
      record with private
                 something: some_type;
      and record;

private

   type T is tagged with
      record
           ID : Integer;
      end record;

   type T1 is new T with
      record
          thing : some_other_type;
      end record;

end P;

Instead I should do this in two steps.
  1. to extend  private part   and then
  2. to extend  public part
or vice versa.

Due to that type T1 has inheritance_depth = 3
instead of inheritance_depth =  2.

LRM (3.9.1) says:
  Every type extension is a tagged type,
and is EITHER a record extension OR a private
extension of some other tagged type.

    It would be interesting to know what were
the reasons not to allow to have BOTH a record
extension AND a private extension at the same time.

Regards,
Vladimir Olensky