Timeout or agreement

Timeout or agreement

[Meresup]

My problem is to wait for the agreement of a sub routine or raise an
response_error exception on timeout. It's so easy to do it with logical
programming that I don't see the way to do it in a sequential programm. Can
u help?

Explanation :
I send a data to serial port
I'd like to wait for the OK flag of the called procedure or a timeout.
What could be the correct structure????????

may i be more explicit?

[Meresup]

I can try.
Here's what i'm trying to do :

procedure Test_Timeout is

-- Timeout
function Timeout return Boolean is
begin
    delay 10.0;
    return True;
end Timeout;

-- Simulation of waiting a response from a procedure
function Ar return Boolean is
begin
    for I in 1..10 loop
        Put (I);
        delay 0.2;
    end loop;
    return True;
end Ar;

begin
Put("Test de timeout");
-- What can i do to go out this test as soon as any of these conditions are
true?
if Ar or Timeout then
    Put (" Timeout atteint");
end if;
end Test_Timeout;

Re: Timeout or agreement

[Patrick Hohmeyer]

And Meresup wrote :

> My problem is to wait for the agreement of a sub routine or raise an
> response_error exception on timeout. It's so easy to do it with logical
> programming that I don't see the way to do it in a sequential programm.
> Can u help?
> 
> Explanation :
> I send a data to serial port
> I'd like to wait for the OK flag of the called procedure or a timeout.
> What could be the correct structure????????

TASK, what you need is a task.

To do what you want you need a second thread or process (always).
Your logical language seems to encapsulate the thread creation for you,
in Ada you need to define a task or a task type.
This is a rather complicated matter, so search yourself a book /
online tutorial about it.

Another word :
As you probably want to stop the thread waiting on the serial port,
you may run into problems.
Stopping a task in the middle of it's execution can leave the
system in an inconsistent state, so be sure to find a *very* *good*
exemple befor doing it.

Have fun ;-)

-- 
Patrick Hohmeyer

Re: may i be more explicit?

[tmoran]

You want Ada tasking, in particular the "selective accept".

select
  accept Ar_is_done;
    Put("Ar finished");
or delay 10.0;
    Put("Timed out");
end select;
Put("either AR finished or we timed out");

Re: Timeout or agreement

[Meresup]

Thanks a lot everybody!!!!