Re: Filenames in Ada

[Martin Krischik <krischik@users.sourceforge.net>]

Randy Brukardt wrote:

> "Martin Krischik" <krischik@users.sourceforge.net> wrote in message
> news:1653090.31FM62oI6I@linux1.krischik.com...
> ...
>> How does one deal with modern (utf-8) filenames in Ada?
> 
> We talked about this briefly at a recent meeting. We decided it was too
> late to design a proper solution, and virtually all operating systems have
> a way to deal with this anyway. (That is that they take UTF-8 names).
> There's no conceptual problem with putting UTF-8 into a value of type
> String, and as someone else showed, that's typcially supported by Ada
> implementations.

Only Windows wants UTF-16 and extra APIs instead . And that is indeed the
problem I have.

Just a question. I get an NAME_ERROR exception in
Ada.Directories.More_Entries. Is that actually correct? Should the
exception not be in Ada.Directories.Simple_Name?

Only when I convert the name to a string it becomes relevant that it can't
be represented into Latin 1.

See source in

http://cvs.sourceforge.net/viewcvs.py/wikibook-ada/demos/Source/make_m3u.adb?only_with_tag=HEAD&view=markup

> A bigger problem is that Ada (any flavor) has no built-in support for
> UTF-8. I think this is a mistake, but I didn't find much support for
> adding any packages.

Well, that can be rectified with external packages. Text_IO is not as easy
to replace

> It's insane to use Wide_Wide_String to store any 
> significant amount of text, as it would waste nearly 3/4s of the space in
> typical use, so you'd have to use something else (like UTF-8) for storage
> anyway.

Tell the C99 designers. They though that wchar_t should be large enough to
hold all possible values - without defining what "all possible values"
actually is. As it is GNU C defines it as 32 bit.

> Since filenames are implementation-defined anyway, there isn't a whole lot
> of value to standardizing how they're written. So, it's just up to your
> implementer to do something appropriate.

As long as you don't "push them with the nose on it" as we say in Germany:

"An implementation may support Wide_String or Wide_Wide_String variants for
passing filenames if supported by the platform"

they won't do nothing.

Martin
-- 
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Ada programming at: http://ada.krischik.com