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From: Robert A Duff <bobduff@TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: two questions on allocators
Date: Wed, 28 Feb 2018 11:09:10 -0500
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Date: 2018-02-28T11:09:10-05:00
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Mehdi Saada <00120260a@gmail.com> writes:

> I saw that since I (tried to) read the AARM, but didn't really got
> it. Now it's ok. If the problem of these null forbidding hypothetic
> subtypes is that can't have the default null value, why not just require
> the user to give one ?

Don't use "not null"; it's broken as you see.  Instead, do:

    subtype S is T with Predicate => S /= null;

- Bob