Re: describe-char should display the character's Unicode name

[Juri Linkov]

> MB> An input method is not a good solution because while input methods are
> MB> good for heavy use, they're quite annoying to juggle for occasional 
> inputs.
>
> Agreed, there should be a function that gives all the Unicode characters
> as input candidates and the user can select the one he wants quickly (I
> don't see one currently).  An input method wouldn't provide completion
> candidates, so the user has to remember all the names he needs.
>
> Would a few thousand candidates be a problem for completion?  I've only
> seen it with hundreds and it's not slow, but for this maybe maybe we can
> break it down by block name and then character name.

There is no problem with completion in a new function below created
to read a character by its Unicode name or hex number string.  There
is only a small delay when it creates the completion list, and a
longer delay when it displays the *Completions* buffer with all
Unicode names:

Index: lisp/international/mule-cmds.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/international/mule-cmds.el,v
retrieving revision 1.333
diff -c -r1.333 mule-cmds.el
*** lisp/international/mule-cmds.el     15 Jul 2008 18:15:03 -0000      1.333
--- lisp/international/mule-cmds.el     19 Jul 2008 00:35:23 -0000
***************
*** 2846,2855 ****
  (defvar nonascii-insert-offset 0 "This variable is obsolete.")
  (defvar nonascii-translation-table nil "This variable is obsolete.")
  
  (defun ucs-insert (arg)
    "Insert a character of the given Unicode code point.
  Interactively, prompts for a hex string giving the code."
!   (interactive "sUnicode (hex): ")
    (or (integerp arg)
        (setq arg (string-to-number arg 16)))
    (if (or (< arg 0) (> arg #x10FFFF))
--- 2849,2873 ----
  (defvar nonascii-insert-offset 0 "This variable is obsolete.")
  (defvar nonascii-translation-table nil "This variable is obsolete.")
  
+ (defun read-char-by-name (prompt)
+   "Read a character by its Unicode name or hex number string.
+ Display PROMPT and read a string that represent a character
+ by its Unicode property `name' or `old-name'.  It also accepts
+ a hexadecimal number of Unicode code point.  Returns a character
+ as a number."
+   (let (name names)
+     (dotimes (c #x10FFFF)
+       (if (setq name (get-char-code-property c 'name))
+         (setq names (cons (cons name c) names)))
+       (if (setq name (get-char-code-property c 'old-name))
+         (setq names (cons (cons name c) names))))
+     (or (cdr (assoc (setq name (completing-read prompt names)) names))
+       (string-to-number name 16))))
+ 
  (defun ucs-insert (arg)
    "Insert a character of the given Unicode code point.
  Interactively, prompts for a hex string giving the code."
!   (interactive (list (read-char-by-name "Unicode (hex or name): ")))
    (or (integerp arg)
        (setq arg (string-to-number arg 16)))
    (if (or (< arg 0) (> arg #x10FFFF))

-- 
Juri Linkov
http://www.jurta.org/emacs/