On Jan 21, 2008, at 3:56 PM, Dmitry Potapov wrote:

quoted text
> On Mon, Jan 21, 2008 at 02:05:51PM -0500, Kevin Ballard wrote:
>>>
>>> But that is *entirely* a separate issue from "normalization".
>>>
>>> Kevin, you seem to think that normalization is somehow forced on you
>>> by
>>> the "text-as-codepoints" decision, and that is SIMPLY NOT TRUE.
>>> Normalization is a totally separate decision, and it's a STUPID one,
>>> because it breaks so many of the _nice_ properties of using UTF-8.
>>
>> I'm not saying it's forced on you, I'm saying when you treat  
>> filenames
>> as text,
>
> to treat as text could mean different for different people. Some
> may prefer to fi and fi_ligature to be treated as same in some
> context.

Those people can use NFKC/NFKD (compatibility equivalence). As I've  
said before, I'm talking about canonical equivalence, because that  
doesn't lose information like compatibility equivalence does (ex. the  
fi ligature gets turned into fi in compatibility equivalence, but not  
canonical equivalence).

quoted text
>> it DOESN'T MATTER if the string gets normalized. As long as
>> the string remains equivalent,
>
> As matter of fact it does, otherwise characters would be the
> same and we would not have this conversation at all. String
> can be equivalent and not equivalent at the time, because there
> are different equivalent relations. Finally, what HFS+ does
> is even not normalization. In the technote, Apple explains
> that they decompose some characters but not others for better
> compatibility. So, you see, there is a PROBLEM here.

Again, I've specified many times that I'm talking about canonical  
equivalence.

And yes, HFS+ does normalization, it just doesn't use NFD. It uses a  
custom variant. I fail to see how this is a problem.

quoted text
>> Alright, fine. I'm not saying HFS+ is right in storing the normalized
>> version, but I do believe the authors of HFS+ must have had a reason
>> to do that,
>
> I don't say they do that without *any* reason, but I suppose all
> Apple developers in the Copland project had some reasons for they
> did, but the outcome was not very good...

Stupid engineers don't get to work on developing new filesystems. And  
Copland didn't fail because of stupid engineers anyway. If I had to  
blame someone, I'd blame management.

quoted text
>> The only information you lose when doing canonical normalization is
>> what the original byte sequence was.
>
> Not true. You lose the original sequence of *characters*.

Which is only a problem if you care about the byte sequence, which is  
kinda the whole point of my argument.

-Kevin Ballard

-- 
Kevin Ballard
http://kevin.sb.org
kevin@sb.org
http://www.tildesoft.com