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From: "J-P. Rosen" <rosen@adalog.fr>
Newsgroups: comp.lang.ada
Subject: Re: Finalization of library level tasks
Date: Mon, 16 Apr 2018 10:32:59 +0200
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Xref: reader02.eternal-september.org comp.lang.ada:51541
Date: 2018-04-16T10:32:59+02:00
List-Id: <comp.lang.ada>

Le 16/04/2018 à 10:13, Dmitry A. Kazakov a écrit :
> You would terminate descendants (grandchildren) from the rendezvous with
> the child's Terminate:
> 
>    select
>       ...
>    or terminate
>       do -- Hidden rendezvous body
>         ... terminate all descendants
>       end Terminate;
>    else
>       ... spawn new descendants
>    end select;
That's not what I mean. If you have both "terminate" and "select", if
you select "terminate" (and all children are on a select with
terminate), then you can terminate and you were right to select that
branch. But if you select "else", then you can wake up other tasks that
might in turn call your entries, so you were right not to select
"terminate". That's what I call undecidable.

>>> Anyway since T'Callable seems working, there is no need to use the
>>> terminate alternative ever.
>>>
>> No, T'Callable becomes false AFTER the terminate has been selected.
> 
> So GNAT implementation is wrong and this one is illegal?
> 
>    task body T is
>    begin
>       loop
>          exit when not T'Callable;
>          ... -- Do something
>       end loop;
>    end T;
I don't know what Gnat is doing, but while T is normally active,
T'Callable is True. This is clearly an infinite loop.

-- 
J-P. Rosen
Adalog
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