Re: One more string functions change

[Eli Zaretskii]

> Date: Sun, 29 Jun 2014 06:53:45 +0400
> From: Dmitry Antipov <address@hidden>
> CC: Kenichi Handa <address@hidden>, address@hidden
> 
> On 06/28/2014 09:19 PM, Eli Zaretskii wrote:
> 
> > UAX#14, UAX#15, UTS#10, and UTS#18 should all be supported by Emacs.
> > (And yes, I should complete my work on bringing the bidirectional
> > editing support in line with the additions to UAX#9 in Unicode 6.3.)
> 
> BTW, why do not use ICU plus our own special handling for 0x110000..0x3FFFFF?

I don't think this was ever considered.

It's possible that we should consider this now, but the answer to your
question is not a trivial one in any case.  Emacs traditionally
exposed to Lisp all the Unicode character properties, as char-tables.
If we decide to use ICU, we'd need to think what to do with those
char-tables: remove them, populate them using ICU, something else?
(Having these databases twice would be an unnecessary bloat, IMO.)
Some of these properties need to support very fast access (e.g., for
bidi display), and the question is how fast is ICU in this regard.
Also, many Unicode features are already implemented, so they should be
reworked or refactored, or maybe the corresponding ICU features left
unused.  And features that depend on Unicode, like font selection,
will have to be adapted.

IOW, just coming up with a list of pros and cons will probably require
some research, IMO.