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Date: Tue, 29 May 2018 10:20:17 -0700 (PDT)
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Subject: Re: why "unconstrained subtype in component declaration" while said
 component given default value ?
From: Mehdi Saada <00120260a@gmail.com>
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Xref: reader02.eternal-september.org comp.lang.ada:52764
Date: 2018-05-29T10:20:17-07:00
List-Id: <comp.lang.ada>

>   type Unconstrained_Collection
>     (Maximum_Size : Positive) is new Abstract_Collection with private;

>   subtype Collection
>      is Unconstrained_Collection (Maximum_Size => Maximum_Size);

It's close, but I would like to hide publicly the discriminants. I would like:
one unconstrained subtype with (<>) which needs initialization, and one subtype who doesn't need it. In fact, I don't need necessarily subtypes:
I could have:
type A(<>) is private;
type B is private;
private
  type A( - discriminants with or without defaults -) is ...
  subtype B is A ( some values); -- not possible, I already complained about it.

I can already get what I want if B is made a derived type of A. No need for tagged types here.