Question

I write a simple emacs mode. How do I explicitly specify that all things in e.g. square brackets should be colored. Must be smth like that:

( (if thing is in square brackets) . font-lock-string-face)

Answer 1

I assume you’re writing a major mode, but font-lock-add-keywords works also in minor
modes. Check out its documentation with C-h f RET font-lock-add-keywords.

(define-derived-mode my-mode text-mode "mymode"
  ;; some init code
  (font-lock-add-keywords nil '(("\\[\\(.*\\)\\]"
                                 1 font-lock-warning-face prepend)))
  ;; some more init code
)