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From: AdaMagica <christoph.grein@eurocopter.com>
Newsgroups: comp.lang.ada
Subject: Re: Enforcing initialization protocol for protected type
Date: Thu, 10 Sep 2009 22:01:17 -0700 (PDT)
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Date: 2009-09-10T22:01:17-07:00
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On 7 Sep., 22:19, Maciej Sobczak <see.my.homep...@gmail.com> wrote:
> type State is private;
> type State_Ptr is access State;
>
> function Make_PO return State_Ptr;
> function Make_PO (Some : T; Parameters : T) return State_Ptr;
> -- ...
>
> protected type PO (S : State_Ptr) is
> -- ...
> private
>     St : State_Ptr := S;
> end PO;
>
> so that the typical creation pattern would be:
>
> X : PO (Make_PO);
> Y : PO (Make_PO (ABC, DEF));
>
> This, however, opens another question: controlled finalization of
> protected types to release the state object, if it was allocated
> dynamically. Oops.

Use an access discriminant of an anonymous type and you will get a
coextension that is reclaimed automatically when the object goes out
of scope, see RM 3.10(14.3/2,14.4/2) [or in the newest draft of the
Amendment 2, (14.1/3,14.4/3), which is a bit clearer].

See also RM 3.7(1.c/2..1.e/2).

> But a controlled component of the protected type can take care of
> that.
> Does it make sense?
>
> --
> Maciej Sobczak *www.msobczak.com*www.inspirel.com
>
> Database Access Library for Ada:www.inspirel.com/soci-ada