Copy or Paste using one and the same key ("C-c c")

copy-and-paste-one-key.el

;;; Copy or Paste using one and the same key ("C-c c")

(defun copy-or-paste ()
  "Copy when there are selected text, paste otherwise."
  (interactive)
  (if (region-active-p)
      (copy-region-as-kill (region-beginning) ; Copy
                           (region-end))
    ;; TODO: deactive mark/region
    ;; Paste
    (yank)))

(global-set-key (kbd "C-c c") 'copy-or-paste)