Emacs flymake mode for ruby

ruby-flymake.el

(require 'flymake)

;; I don't like the default colors :)
(set-face-background 'flymake-errline "red4")
(set-face-background 'flymake-warnline "dark slate blue")

;; Invoke ruby with '-c' to get syntax checking
(defun flymake-ruby-init ()
  (let* ((temp-file   (flymake-init-create-temp-buffer-copy
                       'flymake-create-temp-inplace))
	 (local-file  (file-relative-name
                       temp-file
                       (file-name-directory buffer-file-name))))
    (list "ruby" (list "-c" local-file))))

(push '(".+\\.rb$" flymake-ruby-init) flymake-allowed-file-name-masks)
(push '("Rakefile$" flymake-ruby-init) flymake-allowed-file-name-masks)

(push '("^\\(.*\\):\\([0-9]+\\): \\(.*\\)$" 1 2 nil 3) flymake-err-line-patterns)

(add-hook 'ruby-mode-hook 'flymake-mode)