;;; You may also want to bind hide-body, hide-subtree, show-substree,
;;; show-all, show-children, ... to some keys easy folding and unfolding
(add-hook 'ruby-mode-hook
'(lambda ()
(outline-minor-mode)
(setq outline-regexp " *\\(def \\|class\\|module\\)")))
; Outline-minor-mode key map
(global-set-key [M-left] 'hide-body)
(global-set-key [M-right] 'show-all)
(global-set-key [M-up] 'hide-entry)
(global-set-key [M-down] 'show-entry)
Then use M plus arrow keys to fold and open method/class/module blocks.
M-left will fold all.
M-right will open all.
M-down will open current block.
M-up will close current block.