(defun diff-buffer-against-file (context)
  "diff the current (edited) buffer against the file of the same name"
  (interactive "P")
  (let (($file (concat "\"" buffer-file-name "\""))
	($temp_buffer "emacs.diff")
	($temp_file "/tmp/emacs.diff"))

    (delete-other-windows)
    (push-mark (point) t)
    (generate-new-buffer $temp_file)
    (copy-to-buffer $temp_buffer (point-min) (point-max))
    (set-buffer $temp_buffer)
    (write-file $temp_file)
    (shell-command (concat (if context "diff -c " "diff ") $file " " $temp_file))
    (kill-buffer $temp_file)
    (pop-mark)
    )
  )