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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Operating System differences and Ada OS independent programming
Date: Thu, 24 Mar 2016 09:00:57 +0100
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Date: 2016-03-24T09:00:57+01:00
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On 2016-03-23 16:08, G.B. wrote:
> On 23.03.16 09:38, Dmitry A. Kazakov wrote:
>> For anything impossible under the given OS Use_Error is propagated.
>
> In some cases a substitution mechanism might work:
> If "E:\" is covered by some "multiple roots" type,
> and the filesystem is Unix style, the Use_Error
> could be staged, and conditional. The run-time
> support that establishes the type's associated behavior
> (or path mapping) would be configurable. The
> programmer specifies a mapping mechanism from the
> "multiple roots" object representing "E:\" to some
> other "multiple roots" object that can play the
> same role on his or her system.  Provided, maybe,
> that the original object did not specifically use
> "root-ness", which could be reflected in some constant
> property preventing the above mentioned mapping.
>
> So, then, Use_Error would be raised either
>
> - if the mapping could not be performed because the
>    target object would not represent "root-ness",
>
> - or if no mapping was provided by the programmer,
>
> - or if the mapping "tampers with file systems",
>
> - or if the run-time system does not support mapping.

The mapping is normally predefined. E.g. when you run MinGW, Windows 
roots are already mapped:

    E:\  ->  /e/

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