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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Type_Invariant and Finalize
Date: Thu, 17 Jul 2014 21:49:34 +0100
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Date: 2014-07-17T21:49:34+01:00
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Natasha Kerensikova <lithiumcat@instinctive.eu> writes:

> The latest example is a sorted array of non-null
> paccess-to-indefinite-type values, where the "sortedness" is a natural
> type inveriant, but in Finalize I release the memory using an instance
> of Unchecked_Deallocation.

I don't think these can be null-excluding access types, because you
can't instantiate Unchecked_Deallocation for such a type?

> Or should I prepare for it, e.g. with an explicit boolean record
> component that is False for the most of the lifetime of the object,
> until the first call to Finalize?

This approach is normal, if finalization isn't naturally idempotent.
Sometimes one can use an already-present access value which, if null,
means the object has already been finalized.