我該如何改進Emacs lisp功能？

Question

意圖是使用git grep作爲M-x grep的命令，以及隨之而來的所有緩衝區優勢。所需的功能：

• 它讀取點作爲默認值的字/件事（做，那種）
• 它讀取當前區域作爲缺省參數，如果區域設置。

以下是我到目前爲止的代碼：

(defun bw-read-string-at-point() 
    (interactive) 
    (let ((word (word-at-point))) 
    (set-text-properties 0 (length word) nil word) 
    word)) 

(defun bw-git-grep (search-str) 
    "Uses `git-grep` to find `search-str`" 
    (interactive 
    (list 
    (read-string (format "Search for (%s): " (bw-read-string-at-point))))) 
    (let ((search-str (if (= (length search-str) 0) 
         (bw-read-string-at-point) search-str))) 
    (grep (concat "git --no-pager grep -i -I -nH --no-color --extended-regexp " search-str)))) 

我覺得像interactive位有相當笨拙，可以作出更好的。

Answer 1

其實它看起來不錯。除了你應該使用default' argument of讀取字符串，並且bw-read-string-at-point中的interactive不應該在那裏。或者更好，只需使用grep-tag-default即可。 以下是我想調整它：

(defun bw-git-grep (search-str) 
    "Uses `git-grep` to find `search-str`" 
    (interactive 
    (let ((default (grep-tag-default))) 
    (list 
    (read-string (format "Search for (default %s): " default) 
        nil nil default)))) 
    (grep (concat "git --no-pager grep -i -I -nH --no-color --extended-regexp " search-str))) 

Answer 2

我會用read-from-minibuffer代替read-string：

(defun bw-git-grep (pattern) 
    (interactive 
    (list 
    (read-from-minibuffer 
    "Search for: " 
    (if (region-active-p) 
     (buffer-substring-no-properties (region-beginning) (region-end)) 
     (thing-at-point 'word))))) 

    (let* ((grep-command "git --no-pager grep -i -I -nH --no-color --extended-regexp ") 
     (command  (concat grep-command pattern)) 
     (grep-use-null-device nil)) 
    (grep command))) 

此外，你可能需要確保grep-use-null-device是零，以避免grep附加/dev/null到您的命令（git似乎並不喜歡太多）