comment region/line

(defmacro allow-line-as-region-for-function (orig-function)
`(defun ,(intern (concat (symbol-name orig-function) "-or-line"))
   ()
   ,(format "Like `%s', but acts on the current line if mark is not active." orig-function)
   (interactive)
   (if mark-active
       (call-interactively (function ,orig-function))
     (save-excursion
       ;; define a region (temporarily) -- so any C-u prefixes etc. are preserved.
       (beginning-of-line)
       (set-mark (point))
       (end-of-line)
       (call-interactively (function ,orig-function))))))
 
(allow-line-as-region-for-function comment-region)
(allow-line-as-region-for-function uncomment-region)
(allow-line-as-region-for-function comment-or-uncomment-region)