Re: strange behaviour of utf-8 files

[Stoik <staszek.goldstein@gmail.com>]

W dniu sobota, 16 listopada 2013 16:57:56 UTC+1 użytkownik Dmitry A. Kazakov napisał:
> On Sat, 16 Nov 2013 07:12:20 -0800 (PST), Stoik wrote:
> 
> 
> 
> > By the way, nothing changes if I use wide_character and wide_string
> 
> > instead of character and string. Even if character=octet, certainly
> 
> > wide_character is not an octet!
> 
> 
> 
> String = Latin1
> 
> Wide_String = UCS-2
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> 
> 
> There is no built-in type for UTF-8, though customary one uses String for
> 
> it (and Wide_String for UTF-16).
> 
> 
> 
> -- 
> 
> Regards,
> 
> Dmitry A. Kazakov
> 
> http://www.dmitry-kazakov.de

Thanks for your comments. It is obviously a question of having a different encoding in the editor and the compiler. I forgot to add the -gnatW8 switch to the compiler (this should be a default, I believe). Nevertheless, there still are some misunderstanding connected with string, wide_string and wide_wide_string. They do not correspond to any encodings, they just correspond to character repertoires of the encodings you mentioned. String to the first 256 characters from Unicode (or ISO-10646), wide_string to BMP, and wide_wide_string to the whole Unicode. In particular, wide_string can be encoded internally using any of utf-8,16,32, the programmer does not need to know anything about it. 

I do not believe one should avoid using characters from outside ASCII in the source code. I tried it in Python and Java with no problems whatsoever. Using some strange constants instead of usual glyphs for characters outside ASCII when using subprograms from ada.(wide_)strings.maps, for example to_mapping, would be gruesome. 

In any case, GNAT is prepared to deal with the problem properly, although the number of steps the user must remember about is a bit too high (setting environment variable charset to utf-8, choosing utf-8 in the source editor,adding -gnatW8 to the compiler switches and -W8 to pretty printer switches. And the UTF-8 is the only encoding that solves the problem of non-Latin1 characters at all.

Regards