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From: "J-P. Rosen" <rosen@adalog.fr>
Newsgroups: comp.lang.ada
Subject: Re: confusion about message passing between the tasks
Date: Mon, 27 Oct 2014 08:44:38 +0100
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Date: 2014-10-27T08:44:38+01:00
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Le 26/10/2014 21:31, Robert A Duff a écrit :
> Robert A Duff <bobduff@shell01.TheWorld.com> writes:
> 
>> OK, then I'll make a stronger claim: Everything you can do with
>> rendezvous you can do with (something like) protected objects,
>> and do it just as cleanly, and sometimes even better.
> 
> ...but the other way around isn't true.  Here's Tucker's example that
> convinced me that some sort of "pragma Passive(Buffer_Task);" wasn't
> going to cut it.  Write a PO a that is in one of two states,
> "accepting calls to Entry_1" and "accepting calls to Entry_2",
> never in both states at the same time, and never in neither state
> (as observed by callers).  Pretty easy.  With rendezvous, not so
> much.
> 
> - Bob
> 
Huh?

type states is (state1, state2);
Current_State : States;
...

loop
   select
      when Current_State = State1 =>
         accept RDV1 do... end RDV1;
      when Current_State = State2 =>
         accept RDV2 do ... end RDV2;
   end select;
end loop;

-- 
J-P. Rosen
Adalog
2 rue du Docteur Lombard, 92441 Issy-les-Moulineaux CEDEX
Tel: +33 1 45 29 21 52, Fax: +33 1 45 29 25 00
http://www.adalog.fr