[emacs] Изменение аттрибутов текста

`face'
     You can use the property `face' to control the font and color of
     text.  *Note Faces::, for more information.

     In the simplest case, the value is a face name.  It can also be a
     list; then each element can be any of these possibilities;

        * A face name (a symbol or string).

        * A property list of face attributes.  This has the form
          (KEYWORD VALUE ...), where each KEYWORD is a face attribute
          name and VALUE is a meaningful value for that attribute.
          With this feature, you do not need to create a face each time
          you want to specify a particular attribute for certain text.
          *Note Face Attributes::.

        * A cons cell with the form `(foreground-color . COLOR-NAME)'
          or `(background-color . COLOR-NAME)'.  These are older,
          deprecated equivalents for `(:foreground COLOR-NAME)' and
          `(:background COLOR-NAME)'.  Please convert code that uses
          them.

     It works to use the latter two forms directly as the value of the
     `face' property.

     Font Lock mode (*note Font Lock Mode::) works in most buffers by
     dynamically updating the `face' property of characters based on
     the context.

(defun colorize-region (from to &optional ask-for-color)
  (interactive "r\nP")
  (let ((bg-color (if ask-for-color
                   (read-color "Color:")
                 "red")))
    (put-text-property from to 'face '(:background bg-color))))

(defun colorize-overlay (from to &optional ask-for-color)
  (interactive "r\nP")
  (let ((bg-color (if ask-for-color
                      (read-color "Color: ")
                       "red"))
        (text-to-colorize (make-overlay from to)))
    (overlay-put text-to-colorize 'face (list :background bg-color))))