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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Seeking for papers about tagged types vs access to subprograms
Date: Wed, 15 May 2013 12:10:49 +0200
Organization: cbb software GmbH
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Date: 2013-05-15T12:10:49+02:00
List-Id: <comp.lang.ada>

On Tue, 14 May 2013 16:00:46 -0400, Robert A Duff wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> 
>> IMO, RSX and VMS were precursors of type-safe (one could say an OO) file
>> system which never came to life.
> 
> I'd love to see a type-safe file system.  I've thought a lot about
> how to design such a thing, and I don't think it's easy.  Ada types
> don't work, because they vanish when the program exits, whereas files
> out-live programs.

They would continue to live in the OS. Files could be viewed as persistent
objects.

I agree that in existing Ada would be difficult, because it does not
properly separate representation, which you would like to be able to change
as the OS evolves. E.g. record members should be operations etc.

Then Ada lacks protection against intentional misuse. It should allow
making private stuff memory protected.

There are general issues with typed OS interfaces. E.g. when putting stuff
into a DLL, it does not work well unless drastically limited to very
primitive set of subprograms and basic types like int and char *.

I think that CS in general is not ready for this, as any innovation in the
area of OS design was trumped down by Linux and Windows for decades. The
focus was shifted to services and garbage protocols.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de