On 5 Apr 2017, at 09:09, Jean-Daniel <mail...@xenonium.com> wrote: > >> Le 5 avr. 2017 à 07:49, Gerriet M. Denkmann <gerri...@icloud.com> a écrit : >> >> Apple uses (as far as I remember) a variant of Unicode’s canonical >> decomposition form. > > Yes they do. I think is due to lack of backward compatibility for > normalisation. I don’t think a string normalized in new Unicode version is > guarantee to have the same normalization in past version.
IIRC this happened because HFS+ predates the stability rule in Unicode; as a result, Apple had to fix the normalisation form it used in HFS+, and subsequently Unicode diverged from that *before* the stability rule came into effect. A new filesystem with the same problem could probably rely on the normalisation stability rule to avoid this problem. It would probably need to indicate in the filesystem header the highest version of Unicode that has been used, mind. >> So Apple could use a better normalisation. >> >> But: An existing filename, which is not normalised under the new and better >> normalisation rules, would become inaccessible. Not good. >> Renormalising all filenames according to the new and better normalisation >> rules would be probably rather expensive. >> Also one would need to rename some files, which become identical under the >> new rules. Kind of messy, but not too much. >> >> So I do not really see a way out of this problem (created by some >> questionable decisions of the Unicode people). The problem is that when normalisation *wasn’t* stable, it caused problems whenever any changes were made. So it was “stabilised”, but that meant accepting that anything that wasn’t ideal at that point had to remain that way. The way this is handled in URLs is perhaps informative; IDNA actively prohibits some code points, and then browsers should really also follow the rules in UTS #39 to detect “confusables”. Whether that helps in your specific example case I don’t know. Kind regards, Alastair. -- http://alastairs-place.net _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
