Re: Timeouts in Ada

["Randy Brukardt" <randy@rrsoftware.com>]

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"J-P. Rosen" <rosen@adalog.fr> wrote in message 
news:lq9d2e$2on$1@dont-email.me...
> Le 17/07/2014 22:29, Adam Beneschan a écrit :
>> J-P's statement makes no sense if we're talking about low-level or OS 
>> threads
> I should have included my statement between <lawiers_hat_off> ...
> </lawiers_hat_off>
>
> In practice, and not to confuse the OP, tasks correspond to OS threads.
> I meant that the language does not require creating separate threads
> when not explicitely stated. Of course, a crazy implementation can do it
> any way it pleases, provided it is equivalent to the model.

Nothing crazy about it for implementing ATC. I remember talking about doing 
exactly that when Ada 9x was designed, and the rules were supposed to allow 
it. But it does require some hoops vis-a-vis exceptions, current task, etc.

ATC isn't useful on Windows unless one uses two threads, as most OS calls 
cannot be interrupted. The first example in the RM - 9.7.4(11) will never 
work on Windows unless a two thread model is used. We just discussed that in 
the ARG meeting -- in your office no less -- I'm surprised that you forgot 
about it.

Of course, we decided that it's not important that ATC is useful. (We added 
a disclaimer that cannot possibly be true of the first example.) Ergo, 
talking about ATC is a waste of time, no one should use it because you can't 
expect it to work (portably).

                                                 Randy.