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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: time of update of new values for out mode parameters
Date: Tue, 20 Mar 2018 05:54:46 +0000
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Date: 2018-03-20T05:54:46+00:00
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Mehdi Saada <00120260a@gmail.com> writes:

> Ok. To be honest, the use case I had in mind was a wrong one, is meant
> to be implemented through protected types.
>
> let's say:
> procedure FOO (A: out A_TYPE) is
> ... A := something; -- Can't know when it's copied back
> procedure FOO2 (a: access A_TYPE) is
> ... A.all := something; -- Can't know for sure either, right ?

All you can say is that it will have been copied out by the time you've
returned from the calls. But that must be enough; if there were two
threads making the different calls, how would you be able to tell which
made the earlier call?

> but I am sure with
> until some_absolute_time; some_protected_object.Write(something);
> , and another task can use it safely.
> Now, about procedure FOO (A: out A_TYPE) is
> ... delay until some_absolute_time;
> A := something; delay until the_other_hour;

You are seriously overthinking this.

> I shall assume that inside FOO, A = something" (obviously), but shall
> not assume this for the world outside FOO ?

At the level of Ada code, you have to assume this. How could you
possibly write any sort of reliable program if it were otherwise>?