Emacs funcs.

(if (fboundp 'with-eval-after-load)
    (defmacro after (feature &rest; body)
                             "After FEATURE is loaded, evaluate BODY."
                             (declare (indent defun))
                             `(with-eval-after-load ,feature ,@body))
      (defmacro after (feature &rest; body)
                               "After FEATURE is loaded, evaluate BODY."
                               (declare (indent defun))
                               `(eval-after-load ,feature
                                  '(progn ,@body))))))

(defun default-font-width ()
  "Return the width in pixels of a character in the current
window's default font.  More precisely, this returns the
width of the letter ‘m’.  If the font is mono-spaced, this
will also be the width of all other printable characters."
  (let ((window (selected-window))
  (let ((window (selected-window))
  (let ((window (selected-window))
  (let ((window (selected-window))
        (remapping face-remapping-alist))
    (with-temp-buffer
      (make-local-variable 'face-remapping-alist)
      (setq face-remapping-alist remapping)
      (set-window-buffer window (current-buffer))
      (insert "m")
      (aref (aref (font-get-glyphs (font-at 1) 1 2) 0) 4))))

;;简易的，只能为指定的文件处理为只读
(define-derived-mode org-read-only-mode org-mode "Org + read-only"
  "Major mode for readonly org file."
  (read-only-mode 1))
(add-to-list 'auto-mode-alist '("\\FILE.org\\'" . org-read-only-mode))

;;统一处理，设置了一个钩子
(defvar read-only-file-list
  (list (expand-file-name "~/test.org")))
(defun enable-read-only-fn ()
  (when (member (expand-file-name (buffer-file-name)) read-only-file-list)
    (read-only-mode 1)))
(add-hook 'find-file-hook #'enable-read-only-fn)

(defun sl-toggle-tab-width-setting ()
  "Toggle setting tab widths between 4 and 8."
  (interactive)
  (setq-local tab-width (case tab-width (2 4) (4 8) (8 2)))
  (setq-local c-basic-offset tab-width)
  (redraw-display)
  (message "tab-width is %s now" tab-width))

(eval-after-load 'hideshow
  '(progn
     (declare-function 'hs-already-hidden-p "hideshow")
     (declare-function 'hs-show-all "hideshow")
     (declare-function 'hs-hide-all "hideshow")
     (defun sl-toggle-hideshow-all ()
       "Toggle hideshow all."
       (interactive)
       (hs-life-goes-on
        (if (hs-already-hidden-p)
            (hs-show-all)
          (hs-hide-all))))

     (define-key-after
       hs-minor-mode-menu
       [\(SL\)Toggle\ Show/Hide\ all]
       '(menu-item "(SL)Toggle Show/Hide all..." sl-toggle-hideshow-all
                   :help "Toggle Show/Hide all in current buffer..")
       'Toggle\ Hiding)

     (define-key hs-minor-mode-map (kbd "C-M-;") 'sl-toggle-hideshow-all)
     (define-key hs-minor-mode-map (kbd "C-l ;") 'hs-toggle-hiding)))

(add-hook 'c-mode-common-hook
          (lambda ()
            ;; c/c++ common settings
            (declare-function c-toggle-hungry-state "cc-cmds")
            (c-toggle-hungry-state 1)
            ;; (c-toggle-auto-hungry-state 1) ; hungry-delete and auto-newline
            ;; (c-set-offset 'case-label '+) ; indent the case

            ;; for c++11 as default
            (when (eq major-mode 'c++-mode)
              (when (boundp 'company-clang-arguments)
                (setq-local company-clang-arguments (add-to-list 'company-clang-arguments "--std=c++11"))))
            ))