Re: Interpretation of extensions different from Unix/Linux?

["Jeffrey R. Carter" <spam.jrcarter.not@spam.acm.org>]

Dmitry A. Kazakov wrote:
> 
> Not so. The situation is same as with Ada tasks. Ada does not try to
> provide all possible tasking operations, processes, threads, fibers etc.
> Instead of that it provides a model of concurrent computing that can be
> mapped to practically any OS. This is what I consider portable. The same
> can be done to abstract file systems. We do not need to provide all
> operations of concrete file systems, we have to the operation one has in
> mind working with a file system.

I don't think the situations are precisely the same; Ada tasking can be 
implemented on systems with no OS. It would be somewhat more difficult to 
implement an abstraction of a file system on a system with no file system.

> Hmm, I see no problem with that. I would change Compose, just one more
> argument:
> 
> type Absolute_Path is private;
> type Simple_Name is private;
> type File_Extension is private;
> type File_Version is range <implementation-defined>;
> 
> function Compose
> (  Containing_Directory : Absolute_Path := Current_Directory;
>    Name : Simple_Name;
>    Extension : File_Extension := No_Extension;
>    Version : File_Version := File_Version'First
> ) return Absolute_Path;
> 
> For a file system without versions the only valid File_Version will be 1.

I think there would be more to it than that. You need to deal with roots, 
including none, single, and multiple; with "devices, ... mount points, URL, 
URI", even on file systems that have no concept of them; with comparing and 
canonizing file names; with file names that cannot be represented by a String.

And I'd think this would need to extend beyond Ada.Directories to all of the 
standard I/O pkgs.

-- 
Jeff Carter
"My legs are gray, my ears are gnarled, my eyes are old and bent."
Monty Python's Life of Brian
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