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From: T.G. <anon@anon.org>
Newsgroups: comp.lang.ada
Subject: Abortable Timed Action
Date: Thu, 31 Dec 2015 04:15:13 +0000 (UTC)
Organization: Netfront http://www.netfront.net/
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Xref: news.eternal-september.org comp.lang.ada:28945
Date: 2015-12-31T04:15:13+00:00
List-Id: <comp.lang.ada>

Hello everyone. Is there a better way to implement a timed action?
I've tried the following :

   task type Timed_Action_Task is
     entry Exec_After (T : Duration);
     entry Cancel;
     entry Finish;
   end Timed_Action_Task;

   task body Timed_Action_Task is
      Timeout : Duration;
   begin
      loop
         select
            accept Exec_After (T : Duration) do
               Timeout := T;
            end Exec_After;
            select
               accept Cancel;
            or
               delay Timeout;
               Do_Something;
            end select;
         or
            accept Finish;
            exit;
         end select;
      end loop;
   end Timed_Action_Task;

and then later something like

  Timed_Action.Exec_After (5.0);
  ...
  if Something_Changed then
     Timed_Action.Cancel;
  end if;

it works, I've also tried,

   task body Timed_Action_Task is
      Timeout  : Duration := Duration'Last;
   begin
      loop
         select
            accept Exec_After (T : Duration) do
               Timeout := T;
            end Exec_After;
         or
            accept Cancel;
            Timeout := Duration'Last;
         or
            accept Finish;
            exit;
         or
            delay Timeout;
            Do_Something;
            Timeout := Duration'Last;
         end select;
      end loop;
   end Timed_Action_Task;

any other options?

Regards,


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