Hydra for Unicode input in emacs
Sean Miller recently wrote a blog entry on emacs input methods and
mentioned the prefix key
C-x 8. Almost any character can be printed
out with the help from the prefix key (see
Internally Emacs uses a character encoding that is a superset of
Unicode, so any conceivable character can be used. The problem is to
remember the key combinations to call them out.
I have used the abbrev mode to get some characters that not in my
ccc and space prints out "°C" and
8eur gives me "€".
Sean uses a custom function to get out a certain non-printing
character (ZERO WIDTH SPACE), and points to a more generic solution in
Sacha Chua's emacs config. That calls out Unicode characters by name
from a built-in emacs list (
C-h v ucs-names) using a macro.
Unfortunately this does not solve the problem of how to remember the
keys to call this macro with different Unicode name strings.
For me, the solution was to use the hydra emacs package that both binds keys in very flexible ways to functions and contains a documentation string that is displayed in the emacs echo area. For some reason, the macro did not work with hydra calls but rewriting it to a function fixed it.
(defun my/insert-unicode (unicode-name) "Same as: C-x 8 Enter UNICODE-NAME." (insert-char (cdr (assoc-string unicode-name (ucs-names))))) (global-set-key (kbd "C-x 9") (defhydra hydra-unicode (:hint nil) " Unicode _e_ € _s_ ZERO WIDTH SPACE _f_ ♀ _o_ ° _r_ ♂ _a_ → " ("e" (my/insert-unicode "EURO SIGN")) ("r" (my/insert-unicode "MALE SIGN")) ("f" (my/insert-unicode "FEMALE SIGN")) ("s" (my/insert-unicode "ZERO WIDTH SPACE")) ("o" (my/insert-unicode "DEGREE SIGN")) ("a" (my/insert-unicode "RIGHTWARDS ARROW"))))
C-x 9 displays the list of keys to press next to the
Unicode characters. The list is easy to modify and expand.
Since this the default "red" hydra, it remains active as long as a key that has not been mapped is pressed. Someone should expand this to remap the entire keyboard for mathematical input or to a language with a completely different script – all within emacs.