Question

I conjured up the following code while working on some Vim emulation feature:

If you press ; followed by Return then the cursor will jump to the end of the line and insert a semicolon.

(global-set-key (kbd ";") 'insert-or-append)

(defun insert-or-append ()
  "If the user enters <return>, then jump to end of line and append a semicolon,
   otherwise insert user input at the position of the cursor"
  (interactive)
  (let ((char-read (read-char-exclusive))
        (trigger ";"))
    (if (eql ?\r char-read)
        (progn
          (end-of-line)
          (insert trigger))
      (insert (this-command-keys)))))

This function works alright, but everything is hardcoded. I would prefer to make it more generic. Ideally, I’d like to specify a kbd-macro (for example (kbd "<return>")) as argument and compare it to the result of (read-char). However, kbd returns a symbol and (read-char) returns a character code. I’ve been going over the Emacs documentation, but was unable to find a conversion.

Is there a way to compare the two? Or is there an easier approach?

Answer 1

What about this:

(global-set-key (kbd "RET") 'electric-inline-comment)

(defun electric-inline-comment ()
  (interactive "*")
  (if (and (eq last-command 'self-insert-command)
           (looking-back ";"))
      (progn
        (delete-region (match-beginning 0) (match-end 0))
        (end-of-line)
        (insert ";"))
    (newline)))