demo-code-for-elisp-guide.el

demo-code-for-elisp-guide.el

;;; demo-code-for-elisp-guide.el --- practice code for elisp-guide


;;; Code:

;; Basic concepts

;; Buffers
(current-buffer)
#<buffer demo-code-for-elisp-guide.el>

(buffer-file-name)
"/Users/xcy/gists/demo-code-for-elisp-guide.el"

;; Global variable
(defvar my-name nil "Here should be doc string.")
my-name

;; use it in local buffer
(set (make-local-variable 'my-name) "xoxo")
"xoxo"

;; Project wide buffer-local
;; see ==> (elisp) Directory Local Variables


;; The point
(point)
489
(point-max)
507
(point-min)
1

;; The region
(region-beginning)

(region-end)

(use-region-p)
nil

t

nil

(region-active-p)
595

nil

(defun print-upper-region ()
  "Demo to print the uppercased version of the active region."
  (interactive)
  (when (region-active-p)
    (message "%S" (upcase (buffer-substring (region-beginning)
                                            (region-end))))))

(upcase "skin")

;; 操作 the buffer
(insert "foo" "bar")
foobarnil

(delete-region (1- (point-max)) (point-max))

(insert-buffer-substring-no-properties (get-buffer "*scratch*") 1 3)
myt

(put-text-property 0 1 )
(get-text-property (point-min) )

;; Navigating the buffer
(goto-char (point-min))

(forward-char -1)

(end-of-line)

(beginning-of-line)

(search-backward "line")


;; Save excursion

(save-excursion (beginning-of-line) (looking-at "("))

;;; Query the buffer
(buffer-substring 0 1)
(buffer-substring-no-properties 1 2)
(buffer-string)

(looking-at "[a-zA-Z]+")
(looking-back "[a-zA-Z]+")

;;; Temporary buffers
(with-temp-buffer
  (insert "hello!"))

;;; define interactive function

;; Defining my own major mode
(define-derived-mode hypertext-mode
  text-mode "Hypertext"
  "Major mode for hypertext
\\{hppertext-mode-ma]}")

(define-key hypertext-mode-map
  [down-mouse-3] 'do-hyper link)