Re: Ada.Directories

[Adam Beneschan <adam@irvine.com>]

On Oct 20, 2:21 am, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
wrote:
> Hi all,
>
> I have noticed that GNAT implementation of Ada.Directories.Search "finds"
> the directory being searched and its immediate ancestor in itself (under
> the names "." and ".."). Is it a bug or "feature"? If latter, then I would
> expect at least a special File_Kind value reserved for the mess.

This isn't an easy question.  However, I'd say that it's probably
right to treat "." and ".." as nothing special (at least on Unix-type
system), since that's what I think users expect; they expect to be
able to use "." and ".." as if they were ordinary subdirectory names.
I could be wrong about that.

The flip side is that A.16(45) defines a "directory" as a "container
for files on the target system", and it seems odd to have a directory
containing itself, or its ancestor.  I still think of directory
structures as tree structures, but allowing a directory to contain
itself or its parent makes the structure seem a bit more like a Klein
bottle than a tree.  But since directories on Unix already can contain
references to other directories in other parts of the tree (e.g. hard
links and symbolic links), the structure already isn't a really tree
structure, so I don't see a particular problem with allowing a
directory to contain references to itself and to its parent.  The
"directory" definition has to be somewhat loose anyway, since this
package has to be usable on multiple operating systems.

Maybe the GNAT folks can add a subpackage of Ada.Directories that
contains a routine to control whether "." and ".." are seen as part of
a "directory" file or are treated as invisible.  It seems to me that
it might be appreciated by other users besides Dmitry.  If I used the
Ada.Directories.Search function, I'd probably appreciate the ability
to control this.

                        -- Adam