While not exactly what you need but...

You can try comment-box command together with C-u 20 prefix (or whatever number you want):

You can also write your own function to do it (just grab the sources of the comment-box and try to adjust it to remove 1st and last comment lines + add padding you need).

Now, I had a look into the source code and here we are (not bullet-proof but):

The function to use:

(defun comment-fill-aligned (arg) "Comment out the current line using fill-column to pad and align with comment chars. For the fill-column set to 80 it should look like: elisp: ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; hello ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; c: /************************************* hello *************************************/ " (interactive "p") (comment-normalize-vars) (let* ((comment-style 'aligned) (beg (line-beginning-position)) (end (line-end-position)) (com-add (/ (- fill-column (- end beg)) 2))) (comment-region beg end (+ comment-add com-add)))) 

So eval the function and call it interactively with M-x comment-fill-aligned. It works for the current line.

While not exactly what you need but...

You can try comment-box command together with C-u 20 prefix (or whatever number you want):

You can also write your own function to do it (just grab the sources of the comment-box and try to adjust it to remove 1st and last comment lines + add padding you need).

...

...

...

Now, I had a look into the source code and here we are (not bullet-proof but):

The function to use:

(defun comment-fill-aligned (arg) "Comment out the current line using fill-column to pad and align with comment chars. For the fill-column set to 80 it should look like: elisp: ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; hello ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; c: /************************************* hello *************************************/ " (interactive "p") (comment-normalize-vars) (let* ((comment-style 'aligned) (beg (line-beginning-position)) (end (line-end-position)) (com-add (/ (- fill-column (- end beg)) 2))) (comment-region beg end (+ comment-add com-add)))) 

So eval the function and call it interactively with M-x comment-fill-aligned. It works for the current line.

While not exactly what you need but...

You can try comment-box command together with C-u 20 prefix (or whatever number you want):

You can also write your own function to do it (just grab the sources of the comment-box and try to adjust it to remove 1st and last comment lines + add padding you need).

While not exactly what you need but...

You can try comment-box command together with C-u 20 prefix (or whatever number you want):

You can also write your own function to do it (just grab the sources of the comment-box and try to adjust it to remove 1st and last comment lines + add padding you need).

Now, I had a look into the source code and here we are (not bullet-proof but):

The function to use:

(defun comment-fill-aligned (arg) "Comment out the current line using fill-column to pad and align with comment chars. For the fill-column set to 80 it should look like: elisp: ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; hello ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; c: /************************************* hello *************************************/ " (interactive "p") (comment-normalize-vars) (let* ((comment-style 'aligned) (beg (line-beginning-position)) (end (line-end-position)) (com-add (/ (- fill-column (- end beg)) 2))) (comment-region beg end (+ comment-add com-add)))) 

So eval the function and call it interactively with M-x comment-fill-aligned. It works for the current line.