Transient input methods bound to 'C-x \' (bug#44266)

* lisp/international/mule-cmds.el (ctl-x-map): Bind 'C-x \' to
'transient-input-method'.
(input-method-function): New defcustom.
(transient-input-method): New command.

* doc/emacs/mule.texi (Select Input Method): Document transient-input-method.

1 files changed, 15 insertions, 0 deletions

diff --git a/doc/emacs/mule.texi b/doc/emacs/mule.texi
index b78019020a6..d4ad1d6d5e2 100644
--- a/doc/emacs/mule.texi
+++ b/doc/emacs/mule.texi
@@ -578,6 +578,11 @@ Enable or disable use of the selected input method (@code{toggle-input-method}).
 @item C-x @key{RET} C-\ @var{method} @key{RET}
 Select a new input method for the current buffer (@code{set-input-method}).
 
+@item C-x \ @var{method} @key{RET}
+Temporarily enable the selected transient input method, and
+automatically disable it after inserting a single character
+(@code{transient-input-method}).
+
 @item C-h I @var{method} @key{RET}
 @itemx C-h C-\ @var{method} @key{RET}
 @findex describe-input-method
@@ -675,6 +680,16 @@ character.
 input methods.  The list gives information about each input method,
 including the string that stands for it in the mode line.
 
+@findex transient-input-method
+@kindex C-x \
+  To insert only a single character using a transient input method you
+can first select a transient input method by typing @kbd{C-u C-x \}.
+Then typing @kbd{C-x \} (@code{transient-input-method}) will
+temporarily enable the selected transient input method, and disable it
+automatically after using the activated input method to insert
+a single character.  This is useful to insert a character from input
+methods with rare Unicode characters.
+
 @node Coding Systems
 @section Coding Systems
 @cindex coding systems