Question

I want to copy the line above the cursor, but just from the current column to the end of that line.

Here s an illustration:

photo of before action

photo of result of action

This was my attempt, but it doesn t work so well :-(

(defun dupchar()
  (save-excursion
    (line-move (-1) nil nil nil)
    (setq mychar (thing-at-point  char))
    (insert mychar))

Answer 1

Try something like this.

(defun dupchar ()
  (interactive)
  (let ((char-above (save-excursion
                      (line-move -1)
                      (following-char))))
    (unless (eq char-above ?
)
      (insert char-above))))

(define-key global-map [(meta ")]  dupchar)

A few comments on the function you wrote:

You need to use (interactive) otherwise you can t bind the function to a key.
It s not a good idea to just randomly setq things—that creates a global variable. In this case you don t need a variable at all; you can make use of the return value from save-excursion. (In the later version of this I needed to use a let.)
Parentheses call a function in (e)lisp, so you need to use -1 instead of (-1).
The 2nd-4th arguments to line-move will default to nil, so there s no need to specify them.

(Note: I modified this to stop at the end of the line; it s again hard to understand what you wrote, but this is my best guess.)

Answer 2

not sure if you intended to copy the whole end of the previous line with one keystroke. At least I thought this would be useful so I modified Nicholas (thanks!) code to dupline:

(defun dupline ()
  (interactive)
  (let ((line-above-tail (save-excursion
                           (line-move -1)
                           (buffer-substring-no-properties (point) (line-end-position)))))
    (unless (eq line-above-tail ?
)
      (insert line-above-tail))))

Copying to the end of the line was inspired by How do I duplicate a whole line in Emacs?

友情链接