Re: Can someone please comment on this short program

[Matthias Kaeppler <matthias finitestate org>]

dannym wrote:
> So:
>
> std::string fnIso8859_15Foobar = dirhandle.read_next()->get_name();
> Glib::ustring u8Foobar = filename_to_utf8(fnIso8859_15Foobar);
> Uri uriFoobar = Uri::create(u8Foobar);

Well, except that you renamed the variables, this is what I do :)
That doesn't help solving the problem however.

> Is filename_to_utf8 a glibmm wrapper or the original function? If it is
> a wrapper it should be made to have a signature like:
> Glib::ustring filename_to_utf8(std::string fnSource);
> (if it doesn't have already, that is)

Yes, that's right.

> >   // error! Invalid byte sequence in conversion input
> >   RefPtr<Uri> uri = Uri::create(filename);
>
>
> If the filename is some kind of whack local encoding, this is expected
> and actually good. Think if it didn't notice and you passed the url
> around to some unsuspecting innocent other machine...

I don't think users which use encodings other than UTF-8 (which are 
still prominent by the way) will feel using my filemanager if it breaks 
each time it reads a filename not encoded in UTF-8. So no, this is not a 
good thing :)

> > Uri::create() expects UTF-8, so you /have/ to convert the filename to 
> > UTF-8 using the glib conversion functions:
> >
> >   RefPtr<Uri> uri = Uri::create(filename_to_utf8(filename));
> >
> > No conversion error anymore, but now the Uri object is effectively 
> > useless, because it doesn't point to an existing entity anymore; there 
> > is no file on the system by the name the conversion yields.
>
>
> What do you mean? It should "point" to the right file...

No, it doesn't. That's because special characters such as umlauts have 
different character codes in UTF-8 than they have in ISO. I think my 
initial post showed that this doesn't work:

File "t�":

Filename encoded in ISO-8859-1:
  file:///home/matthias/t%E4st | exists: false

Filename encoded in UTF-8 (and THIS is actually pointing to something, 
although it's the same "name"):
  file:///home/matthias/t%C3%A4st | exists: true

So yes, it does make a difference. Both times the same file, but in 
different encodings; for one the Uri says it doesn't exist, while in the 
other encoding it says it does.

> ... it just passes whatever bytes it finds. So how is glib finding out that
> this filename on that partition is "ISO-8859-1" encoded?

Only by looking at the environment or by the user telling it that 
filenames are encoded in whatever G_FILENAME_ENCODING is holding.

> I really don't see the point in clinging to this anymore, we should just
> make _all_ the filesystem names UTF-8 (or at least look like that to
> userland for filesystems that have assumptions of encoding)...

I very much agree, but that still doesn't solve my problem :)

Regards,
Matthias