A system to save the location (line number) of every file edited with Emacs and let the user jump there with C-l

gistfile1.el

(setq last-location-file (concat my-emacs-d "/last-location"))
(defun load-last-location-file ()
  (if (file-exists-p last-location-file)
      (read (with-temp-buffer
              (insert-file-contents last-location-file)
              (buffer-string)))
  (make-hash-table :test 'equal)))

(setq last-location-table (load-last-location-file))

(defun save-last-location ()
  (puthash (buffer-file-name) (1+ (count-lines 1 (point))) last-location-table))

(add-hook 'kill-buffer-hook 'save-last-location)
(add-hook 'after-save-hook 'save-last-location)

(defun save-all-locations ()
  (progn
    (save-current-buffer
      (mapc '(lambda (buffer)
               (set-buffer buffer)
               (save-last-location))
            (buffer-list)))
    (with-temp-file last-location-file (insert (prin1-to-string last-location-table)))))

(add-hook 'kill-emacs-hook 'save-all-locations)

(defun get-last-location (f)
  (gethash f last-location-table 1))

(defun jump-to-last-location ()
  (interactive)
  (goto-char (point-min)) (forward-line (1- (get-last-location (buffer-file-name)))))

(global-set-key (kbd "C-l") 'jump-to-last-location)