Changing name format for backup files

[Nick Helm]

I like to keep my emacs backup files in the same directory as the file I'm
editing, but I want the backups to be hidden in the GUI by default. I achieve
this by adding a prefix dot to the backup filenames by tweaking
`make-backup-file-name-1' like this:

 (defun make-backup-file-name-1 (file)
   "Subroutine of `make-backup-file-name--default-function'.
 The function `find-backup-file-name' also uses this."
   (let ((alist backup-directory-alist)
        elt backup-directory abs-backup-directory)
     (while alist
       (setq elt (pop alist))
       (if (string-match (car elt) file)
          (setq backup-directory (cdr elt)
                alist nil)))
     ;; If backup-directory is relative, it should be relative to the
     ;; file's directory.  By expanding explicitly here, we avoid
     ;; depending on default-directory.
     (if backup-directory
        (setq abs-backup-directory
              (expand-file-name backup-directory
                                (file-name-directory file))))
     (if (and abs-backup-directory (not (file-exists-p abs-backup-directory)))
        (condition-case nil
            (make-directory abs-backup-directory 'parents)
          (file-error (setq backup-directory nil
                            abs-backup-directory nil))))
     (if (null backup-directory)
 ;; -----------8<------------------CHANGE HERE-----------------8<-------------
 ;;    file
                        (let* ((file-path (file-name-directory file))
                               (file-name (file-name-nondirectory file)))
                            (concat file-path "." file-name))
 ;; -----------8<------------------CHANGE HERE-----------------8<-------------
       (if (file-name-absolute-p backup-directory)
          (progn
            (when (memq system-type '(windows-nt ms-dos cygwin))
              ;; Normalize DOSish file names: downcase the drive
              ;; letter, if any, and replace the leading "x:" with
              ;; "/drive_x".
              (or (file-name-absolute-p file)
                  (setq file (expand-file-name file))) ; make defaults explicit
              ;; Replace any invalid file-name characters (for the
              ;; case of backing up remote files).
              (setq file (expand-file-name (convert-standard-filename file)))
              (if (eq (aref file 1) ?:)
                  (setq file (concat "/"
                                     "drive_"
                                     (char-to-string (downcase (aref file 0)))
                                     (if (eq (aref file 2) ?/)
                                         ""
                                       "/")
                                     (substring file 2)))))
            ;; Make the name unique by substituting directory
            ;; separators.  It may not really be worth bothering about
            ;; doubling `!'s in the original name...
            (expand-file-name
             (subst-char-in-string
              ?/ ?!
              (replace-regexp-in-string "!" "!!" file))
             backup-directory))
        (expand-file-name (file-name-nondirectory file)
                          (file-name-as-directory abs-backup-directory))))))

I do something similar to `make-auto-save-file-name' to achieve the same result
for auto save files.

Redefining core functions seems like a pretty heavy handed approach to the
problem though. Is there better way to achieve the same result? Or perhaps
there's a user option I missed in the manual?

Thanks, 
Nick