如何使用emacs/elisp获取当前缓冲区信息的开始/结束？

Question

我有以下代码来运行将输入作为范围的figlet。如何修改此代码以检查是否未指定b或e，将b设为当前缓冲区的开头，将e设为当前缓冲区的结尾？

(defun figlet-region (&optional b e) 
  (interactive "r")
  (shell-command-on-region b e "/opt/local/bin/figlet" (current-buffer) t)
  (comment-region (mark) (point)))
(global-set-key (kbd "C-c C-x") 'figlet-region)

已添加

肖恩帮我找到了这个问题的答案

(defun figlet-region (&optional b e) 
  (interactive)
  (let ((b (if mark-active (min (point) (mark)) (point-min)))
        (e (if mark-active (max (point) (mark)) (point-max))))
   (shell-command-on-region b e "/opt/local/bin/figlet" (current-buffer) t)
  (comment-region (mark) (point))))
(global-set-key (kbd "C-c C-x") 'figlet-region)

Answer 1

如下所示：

(defun figlet-region (&optional b e) 
  (interactive "r")
  (shell-command-on-region
   (or b (point-min))
   (or e (point-max))
   "/opt/local/bin/figlet" (current-buffer) t)
  (comment-region (mark) (point)))

但请注意，当以交互方式运行此命令时，将始终设置b和e。

你也可以这样做：

(require 'cl)

(defun* figlet-region (&optional (b (point-min)) (e (point-max)))
  # your original function body here
    )

编辑：

所以我猜你的意思是，即使区域处于非活动状态，你也希望能够以交互方式运行该命令？那么这可能会对你起作用：

(defun figlet-region ()
  (interactive)
  (let ((b (if mark-active (min (point) (mark)) (point-min)))
        (e (if mark-active (max (point) (mark)) (point-max))))
    # ... rest of your original function body ...
      ))

Answer 2

试一试

(unless b (setq b (point-min)))
(unless e (setq e (point-max)))