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From: "Jean-Pierre Rosen" <rosen.adalog@wanadoo.fr>
Subject: Re: Streams and Concurrency
Date: 1999/01/04
Message-ID: <76qb23$ba3$1@platane.wanadoo.fr>#1/1
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Date: 1999-01-04T00:00:00+00:00
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dewar@gnat.com a �crit dans le message
<76g9ds$ura$1@nnrp1.dejanews.com>...
>In article <76fe92$46c$1@platane.wanadoo.fr>,
>  "Jean-Pierre Rosen" <rosen.adalog@wanadoo.fr> wrote:
>> Unfortunately, all IO operations are potentially
>> blocking, and therefore not allowed from within a
>> protected operation.
>> To get the effect of mutual exclusion for procedures
>> requiring potentially blocking operations, have a look at
>> package Protection available from Adalog's components
>> page (http://perso.wanadoo.fr/adalog/compo2.htm)
>
>By the way, JPR here seems to be making the mistake of
>assuming that stream = stream_io, a common confusion. The
>original question here related to a particular
>implementation of streams that you have not seen, and you
>do not know if it does any potentially blocking operations.
>
Of course not, but that particular exemple used Text_Streams and I
took this opportunity to remind people of this often overlooked
problem.
Why, if it works on most compilers ? Because I hate concealed design
decisions. Choosing between portability and efficiency (or in this
case, ease of programming) is a trade-off, and it is perfectly
acceptable to disregard portability as long as it is a concious design
decision. But as you noticed, often people make this choice without
being aware of it, and *this* is (IMHO) very bad.
---------------------------------------------------------
           J-P. Rosen (Rosen.Adalog@wanadoo.fr)
Visit Adalog's web site at http://perso.wanadoo.fr/adalog