在 Emacs 中构建和维护数据库？

Question

我正在阅读 Peter Siebel 的书 Practical Common Lisp 的 Simple Database 部分，想法是维护一个包含大约 50,000 条记录的小型数据库。我认为在 Emacs 中执行此操作可能是一个有趣且有用的练习。除了少数notable differences 之外，Emacs Lisp 在某种程度上与 CL 兼容。上述示例中使用的 format 函数是一个主要区别。

这里的代码包含在 CL 中构建、保存和加载数据库所需的一切。这可以修改为在 Emacs 中正常工作吗？我省略了 select 和 where 函数，但我想包括它们。也许有更好的 Emacs 构建和维护数据库的方法？就个人而言，我将其用作学习 CL 和解决现有问题的练习。

;;简单的 Common Lisp 数据库 ;; http://www.gigamonkeys.com/book/practical-a-simple-database.html ;; (defvar *db* 无) （defun make-cd（标题艺术家评级被撕毁） （列表：标题标题：艺术家艺术家：评级等级：撕开撕开）） (defun add-record (cd) (push cd *db*)) (defun转储-db() (dolist (cd *db*) (格式 t"~{~a:~10t~a~%~}~%" cd))) (defun save-db (文件名) (with-open-file (out 文件名 ：方向：输出 :if-exists :supersede) （使用标准 io 语法 （打印 *db* 输出）））） (defun load-db (文件名) （with-open-file（在文件名中） （使用标准 io 语法 (setf *db* (读入))))) ; === ; ;添加一些记录 ; (add-record (make-cd "Roses" "Kathy Mattea" 7 t)) (add-record (make-cd "Fly" "Dixie Chicks" 8 t)) (add-record (make-cd "Home" "Dixie Chicks" 9 t)) ; （转储数据库） ; （保存数据库“cd.db”） ; （加载数据库“cd.db”）

Answer 1

这是我的解决方案：

(defvar *db* nil) (setq *db* ()) (defun make-cd (title artist rating ripped) (list :title title :artist artist :rating rating :ripped ripped)) (defun add-record (cd) (push cd *db*)) (defun init () (progn (add-record (make-cd "Roses" "Kathy Mattea" 7 t)) (add-record (make-cd "Fly" "Dixie Chicks" 8 t)) (add-record (make-cd "Home" "Dixie Chicks" 9 t)) )) (defun save-db (filename) (with-temp-buffer (print *db* (current-buffer)) (write-file filename)) (message "Saving database...done") ) (defun load-db (filename) (with-temp-buffer (insert-file-contents filename) (setq *db* (read (current-buffer))))) (defun dump-db () (dolist (cd *db*) (print cd))) ;; Test in M-x lisp-interaction-mode ;;(init) ;;(save-db "cd.db") ;*db* ;(add-record (make-cd "Born To Run" "Bruce Springsteen" 10 t)) ;(add-record (make-cd "The River" "Bruce Springsteen" 10 t)) ;(add-record (make-cd "Nebraska" "Bruce Springsteen" 10 t)) ;(add-record (make-cd "Human Touch" "Bruce Springsteen" 10 nil)) ;;(save-db "cd.db") ;(setq *db* ()) ;;(load-db "cd.db") ;*db*

Answer 2

当我尝试为 Emacs 编写电子书库时，我将记录存储在一个列表中，不时将其保存到磁盘中。当列表长度超过约五千条记录时，性能受到影响。

以下是代码中的一些函数：

(defun bread-library-load-db ()
 "Loads the list of books from disk file to the variable bread-library-db"
      (if (file-exists-p bread-library-file)
          (with-temp-buffer
        (insert-file-contents bread-library-file)
        (setq bread-library-db (read (current-buffer))))
        (setq bread-library-db '())))

(defun bread-library-add-book (file)
  "Attempts  to   get  metadata  from  file,   then  prompts  for
confirmation (or  modification) of these metadata,  then adds the
book to the database and saves it.  Intended use: from dired."
  (if (assoc file bread-library-db)
      (error "File is already in the database")
    (progn
      (let ((metadata (bread-get-metadata file)))
    (let ((filename (nth 0 metadata))
          (author (read-from-minibuffer 
               "Author: "
               (nth 1 metadata)))
          (title (read-from-minibuffer 
              "Title: "
              (nth 2 metadata)))
          (genre (read-from-minibuffer "Genre: " (nth 3 metadata)))
          (tags (read-from-minibuffer "Tags (separated and surrounded by colons): " ":"))
          (desc (nth 4 metadata)))
      (setq bread-library-db (cons 
                  (list filename author title tags "TOREAD" genre nil desc)
                  bread-library-db))))
      (bread-library-save-db bread-library-db))))

(defun bread-library-save-db (db)
    "Save the library database to a file."
    (message "Saving Bread library database...")
    (with-temp-buffer
      (insert "; 1.path 2.author 3.title 4.tags 5.state 6.genre 7.priority 8.description")
      (print db (current-buffer))
      (write-file bread-library-file))
    (message "Saving Bread library database...done"))