Re: Function for enabling or disabling emacs bars

[Emanuel Berg via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

Here is an interface that I think is consistent with other
minor mode interfaces that are the same (ha).

(defun bars (&optional arg)
 (interactive (list (or current-prefix-arg 'toggle)))
 (menu-bar-mode arg)
 (let ((enable (if menu-bar-mode 1 -1)))
   (scroll-bar-mode enable)
   (tool-bar-mode   enable) ))

;; Lisp use

;; enable on nil arg, no arg (which implies nil), or if arg is positive

(bars)     ; no arg -> optional arg nil -> enable
(bars nil) ; arg is nil -> enable
(bars 1)   ; arg positive -> enable

;;  disable if arg is negative

(bars -1) ; arg negative -> disable

;; toggle if arg is 'toggle

(bars 'toggle)

;; interactive use

;; M-x bars RET -> toggle (hard-coded interactive default)
;; C-u M-x bars RET -> arg is 4 -> arg positive -> enable
;; C-u -1 M-x bars RET -> arg is -1 -> arg negative -> disable

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