Function: backup-extract-version

backup-extract-version is a byte-compiled function defined in files.el.gz.

Signature

(backup-extract-version FN)

Documentation

Given the name of a numeric backup file, FN, return the backup number.

Uses the free variable backup-extract-version-start, whose value should be the index in the name where the version number begins.

Source Code

;; Defined in /usr/src/emacs/lisp/files.el.gz
;; This is used in various files.
;; The usage of backup-extract-version-start is not very clean,
;; but I can't see a good alternative, so as of now I am leaving it alone.
(defun backup-extract-version (fn)
  "Given the name of a numeric backup file, FN, return the backup number.
Uses the free variable `backup-extract-version-start', whose value should be
the index in the name where the version number begins."
  (if (and (string-match "[0-9]+~/?$" fn backup-extract-version-start)
	   (= (match-beginning 0) backup-extract-version-start))
      (string-to-number (substring fn backup-extract-version-start -1))
      0))