Emacs :TODO indicator at left side

Question

I want to have sort of indiacator at left side of the line wherever I have in the source code

#TODO: some comment

//TODO: some comments

The indicator could be a just mark and I already enabled line numbers displayed at emacs.

Answer 1

This command will do something like you want.

(defun annotate-todo ()
  "put fringe marker on TODO: lines in the curent buffer"
  (interactive)
  (save-excursion
    (goto-char (point-min))
    (while (re-search-forward "TODO:" nil t)
      (let ((overlay (make-overlay (- (point) 5) (point))))
        (overlay-put overlay 'before-string (propertize "A"
                                                        'display '(left-fringe right-triangle)))))))

You can customize the bitmap as desired.

To get this to apply to all files, you could add it to the 'find-file-hooks

(add-hook 'find-file-hooks 'annotate-todo)

Or, if you want it just for certain modes, you could add it to those mode hooks.

See Fringes, The 'display' Property, Overlays, and most importantly the before-string property.

Note: The code was updated 27/02/2010 to use overlays instead of directly adding text properties to the current text.

Answer 2

I like the approach described in this post on emacs-fu, which adds TODO/FIXME/... to the font-lock settings of the modes where you need it. In contrast to Trey's approach this should highlight the words as you type, whereas his approach should only highlight them when you open a file (or do I get this wrong).

Anyway its up to you. A good google search gives you probably even more ideas: http://www.google.com/search?q=emacs+highlight+todo

Update: Your question has already been answered: Emacs, highlight all occurences of a word