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From: Stephen Leake <Stephen.A.Leake@nasa.gov>
Newsgroups: comp.lang.ada
Subject: Re: new_line in a put_line
Date: 04 Dec 2002 10:25:47 -0500
Organization: NASA Goddard Space Flight Center (skates.gsfc.nasa.gov)
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Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> writes:

> On 04 Dec 2002 10:31:15 +0100, Fraser Wilson
> <newsfraser@blancolioni.org> wrote:
> 
> >Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> writes:
> >
> >> Just do not do I/O from them. Define a mutex as a protected object and
> >> a spin lock as a controlled type (less troubles with releasing a
> >> mutex):
> >
> >[..]
> >
> >>    procedure Put_Line (Text : String) is
> >>       Get_It : Lock (Write_Mutex'Access);
> >>    begin
> >>       Ada.Text_IO.Put_Line (Text);
> >>    end Put_Line;
> >
> >Something inside me rebels at using side-effects from a declaration
> >like that. 
> 
> Right, right. It is also my opinion [there was a thread regarding this
> subject in c.l.a] that using unused (:-)) objects probably indicates a
> design problem. 

That's what pragma Unreferenced (in GNAT) is for; it documents that
the object is declared only for the hidden effects of Initialize and
Finalize.

Assuming Lock is a controlled type, that releases the lock in
Finalize, this is an excellent design.

-- 
-- Stephe