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-*-mode: text; coding: latin-1;-*-
Copyright (C) 2002-2012 Free Software Foundation, Inc.
See the end of the file for license conditions.
Problems, fixmes and other unicode-related issues
-------------------------------------------------------------
Notes by fx to record various things of variable importance. handa
needs to check them -- don't take too seriously, especially with
regard to completeness.
* SINGLE_BYTE_CHAR_P returns true for Latin-1 characters, which has
undesirable effects. E.g.:
(multibyte-string-p (let ((s "x")) (aset s 0 ?�) s)) => nil
(multibyte-string-p (concat [?�])) => nil
(text-char-description ?�) => "M-#"
These examples are all fixed by the change of 2002-10-14, but
there still exist questionable SINGLE_BYTE_CHAR_P in the
code (keymap.c and print.c).
* Rationalize character syntax and its relationship to the Unicode
database. (Applies mainly to symbol an punctuation syntax.)
* Fontset handling and customization needs work. We want to relate
fonts to scripts, probably based on the Unicode blocks. The
presence of small-repertoire 10646-encoded fonts in XFree 4 is a
pain, not currently worked round.
With the change on 2002-07-26, multiple fonts can be
specified in a fontset for a specific range of characters.
Each range can also be specified by script. Before using
ISO10646 fonts, Emacs checks their repertories to avoid such
fonts that don't have a glyph for a specific character.
fx has worked on fontset customization, but was stymied by
basic problems with the way the default face is dealt with
(and something else, I think). This needs revisiting.
* Work is also needed on charset and coding system priorities.
* The relevant bits of latin1-disp.el need porting (and probably
re-naming/updating). See also cyril-util.el.
* Quail files need more work now the encoding is largely irrelevant.
* What to do with the old coding categories stuff?
* The preferred-coding-system property of charsets should probably be
junked unless it can be made more useful now.
* find-multibyte-characters needs looking at.
* Implement Korean cp949/UHC, BIG5-HKSCS and any other important missing
charsets.
* Lazy-load tables for unify-charset somehow?
Actually, Emacs clears out all charset maps and unify-map just
before dumping, and they are loaded again on demand by the
dumped emacs. But, those maps (char tables) generated while
temacs is running can't be removed from the dumped emacs.
* iso-2022 charsets get unified on i/o.
With the change on 2003-01-06, decoding routines put `charset'
property to decoded text, and iso-2022 encoder pay attention
to it. Thus, for instance, reading and writing by
iso-2022-7bit preserve the original designation sequences.
The property name `preferred-charset' may be better?
We may have to utilize this property to decide a font.
* Revisit locale processing: look at treating the language and
charset parts separately. (Language should affect things like
spelling and calendar, but that's not a Unicode issue.)
* Handle Unicode combining characters usefully, e.g. diacritics, and
handle more scripts specifically (� la Devanagari). There are
issues with canonicalization.
* We need tabular input methods, e.g. for maths symbols. (Not
specific to Unicode.)
* Need multibyte text in menus, e.g. for the above. (Not specific to
Unicode -- see Emacs etc/TODO, but now mostly works with gtk.)
* There's currently no support for Unicode normalization.
* Populate char-width-table correctly for Unicode characters and
worry about what happens when double-width charsets covering
non-CJK characters are unified.
* There are type errors lurking, e.g. in
Fcheck_coding_systems_region. Define ENABLE_CHECKING to find them.
* Old auto-save files, and similar files, such as Gnus drafts,
containing non-ASCII characters probably won't be re-read correctly.
This file is part of GNU Emacs.
GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
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