I have the following code to replace default eldoc display function:

(defun my-eldoc-display-message-momentary (format-string &rest args)
    "Display eldoc message near point."
    (when format-string
      ;; (pos-tip-show (apply 'format format-string args))
       (apply 'format format-string args)
       (save-excursion (forward-line) (point))

(setq eldoc-message-function #'my-eldoc-display-message-momentary)

But it does not work smoothly.

  • it display slowly
  • the exit-char for momentary-string-display should be excepted in most programming code inputting (not SPC, not [a-zA-Z], not [*,-+=!] etc)

Hope someone can improve it.

  • 1
    Would you mind to define the slowness? I've tested the code above but didn't see the slowness, meaning that pos-tip-show version and momentary-string-display version displays in the same timing on my system, as far as I can tell. Would you also tell me about excepted exit-char? What behavior are you looking for? Jan 10, 2017 at 6:59

1 Answer 1


As with the comment, pos-tip-show works fine for me too.

I did hack together a better (but not perfect) version of the momentary-string-display version. I just rewrote the display function so that it deleted the overlay passively through a hook instead of waiting for an exit-char, which doesn't seem appropriate for what you are trying to do. The display function I put together temporarily overwrites the next line of the buffer with the message. See if you like it.

(defvar my-display-overlay nil)

(defun my-delete-string-display ()
  (when (overlayp my-display-overlay)
    (delete-overlay my-display-overlay))
  (remove-hook 'post-command-hook 'my-delete-string-display))

(defun my-string-display-next-line (string)
  "Overwrite contents of next line with STRING until next command."
  (let ((str (concat
               (make-string (1+ (current-indentation)) 32)
               (propertize (copy-sequence string) 'face '(:background "#3e4451" :extend t))))
         (start-pos nil)
         (end-pos nil))
        (setq start-pos (point))
        (setq end-pos (point))
        (setq my-display-overlay (make-overlay start-pos end-pos))
        ;; Hide full line
        (overlay-put my-display-overlay 'display "")
        ;; Display message
        (overlay-put my-display-overlay 'before-string str))
      (add-hook 'post-command-hook 'my-delete-string-display))))

(defun my-eldoc-display-message-momentary (format-string &rest args)
  "Display eldoc message near point."
  (when format-string
    (my-string-display-next-line (apply 'format format-string args))))

(setq eldoc-message-function #'my-eldoc-display-message-momentary)
  • Can you add a face for this overlay? So it can has different background color with 'default face. Thanks. Jan 14, 2017 at 3:00
  • Sure, I added a line to the display function to set a face.
    – justbur
    Jan 14, 2017 at 15:07
  • I added your added line code, but it does not work. And I use your code to created a minor mode github.com/stardiviner/eldoc-overlay-mode Jan 14, 2017 at 15:28
  • Did you change the face? I set it to default but you'll have to change it to see a difference.
    – justbur
    Jan 14, 2017 at 15:38
  • Yes, I changed face. I also define a face for it. Check out my upper link repo's develop branch. Jan 14, 2017 at 16:07

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