Re: Can someone please comment on this short program


On Wed, 14.12.2005, 15:23 +0100 Matthias Kaeppler wrote on
> Alexander Larsson wrote on gnome-vfs-list:
> > I'm not sure where the confusion is. I can't talk for the c++ bindings,
> > but for gnome-vfs itself the rule is:
> > 
> >   * file: URIs have no inherent encoding
> > 
> > None, nada, zilch. They are the filename as stored on disk, escaped into
> > a uri. As such, they are essentially escaped byte strings, the only
> > limit being that zero bytes and '/' bytes are not allowed. This is a
> > direct result of the fact that unix filenames have no encoding, and is
> > nothing we can anything do about in gnome-vfs.
> Yes, I actually think the problem lies in the C++ bindings, because as 
> opposed to gnome_vfs_uri_new(), the construction of a Gnome::Vfs::Uri in 
> gnome-vfsmm requires the string which is passed to Uri::create() to be 
> encoded in UTF-8 

I take it that 
- gnome-vfs supports http:// uris as well
- those need to be utf-8 encoded and escaped then

So one would have to have two different create functions, one for
"file", one for "http" (and everything else?)

> (that's because create() takes a Glib::ustring, 

Yeah, that is probably a mistake...

I would CC murrayc and Bryan Forbes, but their "Authors" file states "do
not email people directly"... sigh... ok, murrayc should be reading this
on this mailinglist either way, I hope :) 

> and if 
> you pass an std::string in place of a Glib::ustring--such as the one 
> returned from FileInfo::get_name()--a conversion attempt will be made).

Curious... a conversion attempt? From what ? It must have found a
crystal ball somewhere :) 

If it does indeed try that, another mistake...

> If the string passed to create() is not valid UTF-8 however, an 
> exception will be raised.

> On the other hand however, if the string used to initialize the 
> Gnome::Vfs::Uri is valid UTF-8 (e.g. after a successful conversion using 
> the glib functions), it is possible that after construction, 
> Gnome::Vfs::Uri::uri_exists() will always return false /if/ the system 
> uses a different encoding for the filename in question.

yes... a follow-up error

> > You just have to be very careful about your string encodings. I'd
> > recommend using hex escapes when specifying a non-ascii string in C
> > source code.
> it's not only about strings which are hardwired into the source code; 
> the problem applies to all other strings as well.

If it is as you say, the bindings probably use Glib::ustring in this
case when they should use something like (a imaginary :))
Glib::opaquestring or somesuch...

(don't we all love the encoding mess :))

> Regards,
> Matthias


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