Home

Customization for ruby-mode.el

Unfortunately the ruby-mode that ships with Emacs 25.x, highlights self like a keyword instead of matching nil, true, and false. It also uses the wrong color to highlight symbols. To fix this when using this theme, add the following to your config:

  (defvar ruby-symbol-face 'ruby-symbol-face)
  (defface ruby-symbol-face
    '((t (:inherit ruby-constant-face)))
    "Syntax highlighting for Ruby symbol."
    :group 'ruby)
  (defvar ruby-constant-face 'ruby-constant-face)
  (defface ruby-constant-face
    '((t (:inherit font-lock-constant-face)))
    "Syntax highlighting for Ruby constant."
    :group 'ruby)


  (defun ruby-syntax-highlight-overrides ()
    (font-lock-add-keywords nil
                            '(;; Singleton objects.
                              ("\\(?:^\\|[^.@$:]\\|\\.\\.\\)\\_<\\(self\\|nil\\|true\\|false\\)\\_>"
                               1 ruby-constant-face)
                              ;; Symbols.
                              ("\\(^\\|[^:]\\)\\(:@\\{0,2\\}\\(?:\\sw\\|\\s_\\)+\\)"
                               (2 ruby-symbol-face)
                               (3 (unless (and (eq (char-before (match-end 3)) ?=)
                                               (eq (char-after (match-end 3)) ?>))
                                    ;; bug#18644
                                    ruby-symbol-face)
                                  nil t))
                              ;; Ruby 1.9-style symbol hash keys.
                              ("\\(?:^\\s *\\|[[{(,]\\s *\\|\\sw\\s +\\)\\(\\(\\sw\\|_\\)+:\\)[^:]"
                               (1 (progn (forward-char -1) ruby-symbol-face)))
                              ))
    )
  (add-hook 'ruby-mode-hook 'ruby-syntax-highlight-overrides)

Spacemacs Users: the above code only works when placed inside the dotspacemacs/user-init function.