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Path: utzoo!attcan!uunet!wuarchive!cs.utexas.edu!swrinde!ucsd!ucbvax!husc6!encore!jcallen
From: jcallen@Encore.COM (Jerry Callen)
Newsgroups: comp.lang.ada
Subject: Re: LRM question - access types and con
Summary: What about I/O?
Message-ID: <12142@encore.Encore.COM>
Date: 28 Jun 90 13:34:57 GMT
References: <1394@software.software.org> <20600054@inmet>
Reply-To: jcallen@encore.com (Jerry Callen)
Organization: Encore Computer Corp, Marlboro, MA
List-Id: <comp.lang.ada>

In article <20600054@inmet> stt@inmet.inmet.com writes:
>The programmer need only worry about declared variables which are shared
>between tasks.  An access collection is not considered an explicitly
>declared variable in this sense.
>The implementation must worry about all "hidden" shared data.
>Therefore, an implementation must protect its run-time data structures
>from simultaneous access.

So what about the built-in I/O packages? Is it safe for multiple tasks
to be issuing, say, Put_Line calls without worrying about synchronization?

[Aside: I think I know what Tucker's response will be; he'll say that the
 I/O packages are just like user packages, they just happen to come with
 the compiler, so they are not required to be "thread-safe."]

I bring this up because it has been a repeated thorn in my side over the
years. I've always felt that, at the very least, the built-in I/O packages
should provide some means of requesting synchronization in the face of
tasking. Maybe a form string parameter?

>S. Tucker Taft
>Intermetrics, Inc.

-- Jerry "RTS hack" Callen
   jcallen@encore.com