Re: good enough for MELPA work?

[Emanuel Berg]

> It (checkdoc) still complains about the first
> line, but that is OK, right? So that is
> a bug, if indeed alright.

Here what it says:

*** isbn-verify.el: checkdoc-current-buffer V 0.6.1
isbn-verify.el:0: The first line should be of the form: ";;; package --- 
Summary"

All other warnings are now gone, I added some
dorky documentation because I can't handle
programs warning me about stuff. It comes with
the territory.

;;; isbn-verify - Verify ISBN-10 and ISBN-13 -*- lexical-binding: t -*-
;;
;;; Commentary:
;;
;; This Elisp package provides functions to
;; verify ISBNs by computing their check
;; digits. The package can be found here:
;;   <https://dataswamp.org/~incal/emacs-init/isbn-verify.el>
;;
;; The package was last modified by Emanuel Berg
;; 2020-02-26. Mail feedback to <moasenwood@zoho.eu>
;; or talk to me at IRC, I'm incal on freenode.
;;
;; For more info on ISBNs and how the check
;; digits are computed, see:
;;   <https://dataswamp.org/~incal/books/isbn.txt>
;;
;; To see how it works, try
;; `check-isbn-at-point' on these two Biblatex
;; entries, the first one with ISBN-10, the
;; second with ISBN-13. Place point at the
;; beginning of the ISBN, then do M-x ciap RET
;;
;; @book{russia-and-the-arms-trade,
;;   author    = {Ian Anthony},
;;   isbn      = {0-19-829278-3},
;;   publisher = {Oxford},
;;   title     = {Russia and the Arms Trade},
;;   year      = 1998
;; }
;;
;; @book{baa-lo-4,
;;   author     = {Yukito Kishiro},
;;   isbn       = {978-1-61262-294-1},
;;   publisher  = {Kodansha},
;;   title      = {Battle Angel Alita: The Last Order 4},
;;   year       = {2014 (2011)}
;; }
;;
;; Or, with Lisp:
;;
;;   (checksum-isbn-10 "0-19-829576-6")     ; 6
;;   (checksum-isbn-13 "978-1-61262-294-1") ; 1
;;
;;; Code:

(require 'cl-lib)

(defun digits-only-string (str)
  "Evaluate into a version of STR, with all non-digits removed."
  (replace-regexp-in-string "[^0-9]" "" str) )

(defun char-to-int (c)
  "Convert a char C into the digit it displays,
e.g., (char-to-int ?9) ; 9"
  (- c ?0))

(defun string-to-integer-list (str)
  "Make an integer list from a string STR.
All non-digits are dropped."
  (let*((digits-only (digits-only-string str))
        (chars       (string-to-list digits-only))
        (ints        (cl-map 'list
                             (lambda (c) (char-to-int c))
                             chars) ))
    ints) )

(defun check-isbn-at-point ()
  "Compute and display the check digit from the ISBN at point.

See \\[checksum-isbn-10] and \\[checksum-isbn-13] for Lisp work."
  (interactive)
  (let*((isbn-string (thing-at-point 'symbol t))
        (digits-only (digits-only-string isbn-string))
        (num-digits  (length digits-only))
        (check-digit (if (> num-digits 10)
                         (checksum-isbn-13 digits-only)
                       (checksum-isbn-10 digits-only) )))
    (message "check digit: %s" check-digit)
    ))
(defalias 'ciap #'check-isbn-at-point)

(defun checksum-isbn-13 (isbn)
  "Compute the checksum for ISBN which should be ISBN-13,
i.e. consist of 13 digits. Because the last digit, number 13,
is the checksum, actually only 12 digits, in the form of a string,
is needed. Hyphens/dashes can be included or omitted.

Also see \\[checksum-isbn-10].

For interactive work, see \\[check-isbn-at-point]."
  (let*((isbn-ints (string-to-integer-list isbn))
        (sum       0))
    (cl-loop for e in isbn-ints
             for i from 0 to 11
             do (progn (message "%d" i)
                       (cl-incf sum (* e (or (and (zerop (mod i 2)) 1) 3)))
                       )
             )
    (let ((checksum (- 10 (mod sum 10))))
      (if (= 10 checksum) 0 checksum) )))

(defun checksum-isbn-10 (isbn)
  "Compute the checksum for ISBN which should be ISBN-10,
i.e. consist of 10 digits. Because the last digit, number 10,
is the checksum, actually only 9 digits, in the form of a string,
is needed. Hyphens/dashes can be included or omitted.

Also see \\[checksum-isbn-13].

For interactive work, see \\[check-isbn-at-point]."
  (let*((isbn-ints (string-to-integer-list isbn))
        (sum       0) )
    (cl-loop for e in isbn-ints
             for i downfrom 10 to 2
             do (cl-incf sum (* e i)) )
    (let ((checksum (mod (- 11 (mod sum 11)) 11)))
      (if (= 10 checksum) "X" checksum) )))

;; 10 ISBN-10 tests:
;;
;; (checksum-isbn-10 "0-201-53992-6") ; 6
;; (checksum-isbn-10 "0312168144")    ; 4
;; (checksum-isbn-10 "1-4012-0622-0") ; 0
;; (checksum-isbn-10 "1616558717")    ; 7
;; (checksum-isbn-10 "91-510-6483-9") ; 9
;; (checksum-isbn-10 "91-7054-940-0") ; 0
;; (checksum-isbn-10 "91-7089-710-7") ; 7
;; (checksum-isbn-10 "91-85668-01-X") ; X
;; (checksum-isbn-10 "91-88930-23-8") ; 8
;; (checksum-isbn-10 "9177988515")    ; 5

;; 13 ISBN-13 tests:
;;
;; (checksum-isbn-13 "91-518-4657-8")     ; 8
;; (checksum-isbn-13 "978-1-63236-616-0") ; 0
;; (checksum-isbn-13 "978-91-0-012814-2") ; 2
;; (checksum-isbn-13 "978-91-29-59023-4") ; 4
;; (checksum-isbn-13 "978-91-7037-681-8") ; 8
;; (checksum-isbn-13 "978-91-7515-205-9") ; 9
;; (checksum-isbn-13 "978-91-7515-317-9") ; 9
;; (checksum-isbn-13 "978-91-86936-31-0") ; 0
;; (checksum-isbn-13 "978-91-87861-54-3") ; 3
;; (checksum-isbn-13 "978-91-87861-67-3") ; 3
;; (checksum-isbn-13 "978-91-87861-99-4") ; 4
;; (checksum-isbn-13 "9780062802187")     ; 7
;; (checksum-isbn-13 "9789188805034")     ; 4

(provide 'isbn-verify)
;;; isbn-verify.el ends here

-- 
underground experts united
http://user.it.uu.se/~embe8573
https://dataswamp.org/~incal