From: Mark Slagell <ms@...>
Date: 2002-07-07T22:53:35+09:00
Subject: Re: hideshow mode for ruby-mode.el

>
>
>>>The `hideshow' Emacs minor mode lets you hide the content of a
>>>      
>>>
>>block
>>    
>>
>>>of code and only see the first line
>>>

There is also emacs' selective-display facility, which shows or hides 
based on the existing indentation. So it basically borrows the logic of 
ruby-mode or whatever.  --Mark

;; ~/.emacs excerpt
;;  Use function keys f9 through f12 as a 'zoom' control.
(defun zoom-way-out() (interactive)
  (set-selective-display 0))
(defun zoom-way-in() (interactive)
  (set-selective-display 2))
(defun zoom-out() (interactive)
 (set-selective-display
  (if selective-display
      (if (or (= selective-display 0) (= selective-display 10))
      0
    (+ selective-display 2))
    0)))
(defun zoom-in() (interactive)
 (set-selective-display
  (if selective-display
      (if (= selective-display 0)
      10
    (if (= selective-display 2)
        2
      (- selective-display 2)))
    10)))

(global-set-key [f9] 'zoom-way-out)
(global-set-key [f10] 'zoom-out)
(global-set-key [f11] 'zoom-in)
(global-set-key [f12] 'zoom-way-in)