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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Finalization of library level tasks
Date: Mon, 16 Apr 2018 10:13:10 +0200
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Xref: reader02.eternal-september.org comp.lang.ada:51540
Date: 2018-04-16T10:13:10+02:00
List-Id: <comp.lang.ada>

On 16/04/2018 09:55, J-P. Rosen wrote:
> Le 16/04/2018 à 09:30, Dmitry A. Kazakov a écrit :
>> On 16/04/2018 07:19, J-P. Rosen wrote:
>>> Le 15/04/2018 à 19:40, Dmitry A. Kazakov a écrit :
>>>> Terminate alternative is almost always useless because it cannot be
>>>> mixed with "else" or "delay".
>>> And make termination undecidable? Come on!
>>
>> Why? Terminate should be a predefined entry the task master calls to.
> If you allowed an else (or delay) alternative together with a terminate,
> that alternative would be selected, and the task could in turn wake-up
> its descendents...

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;

>> 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;

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de