* lisp/calendar/todo-mode.el: Let-bind `inhibit-read-only`

rather than `buffer-read-only`.  Applied throughout the file.
(todo-date-pattern, todo-edit-item--header, todo-convert-legacy-date-time)
(todo-read-date): Remove redundant "" arg to `mapconcat`.

1 files changed, 29 insertions, 31 deletions

diff --git a/lisp/calendar/todo-mode.el b/lisp/calendar/todo-mode.el
index ffb7b7168dd..093ea0e22b6 100644
--- a/lisp/calendar/todo-mode.el
+++ b/lisp/calendar/todo-mode.el
@@ -200,7 +200,7 @@ The final element is \"*\", indicating an unspecified month.")
                  (month "\\(?7:[0-9]+\\|\\*\\)")
                  (day "\\(?8:[0-9]+\\|\\*\\)")
                  (year "-?\\(?9:[0-9]+\\|\\*\\)"))
-              (mapconcat #'eval calendar-date-display-form ""))
+              (mapconcat #'eval calendar-date-display-form))
             "\\)"))
   "Regular expression matching a todo item date header.")
 
@@ -1206,7 +1206,7 @@ visiting the deleted files."
                 (let ((sexp (read (buffer-substring-no-properties
                                    (line-beginning-position)
                                    (line-end-position))))
-                      (buffer-read-only nil)
+                      (inhibit-read-only t)
                       (print-length nil)
                       (print-level nil))
                   (mapc (lambda (x) (aset (cdr x) 3 0)) sexp)
@@ -1304,7 +1304,7 @@ return the new category number."
       (widen)
       (goto-char (point-max))
       (save-excursion                   ; Save point for todo-category-select.
-        (let ((buffer-read-only nil))
+        (let ((inhibit-read-only t))
           (insert todo-category-beg cat "\n\n" todo-category-done "\n")))
       (todo-update-categories-sexp)
       ;; If invoked by user, display the newly added category, if
@@ -1486,7 +1486,7 @@ the archive of the file moved to, creating it if it does not exist."
                                       nfile-short)
                               (format "the category \"%s\";\n" cat)
                               "enter a new category name: "))
-                     (buffer-read-only nil)
+                     (inhibit-read-only t)
                      (print-length nil)
                      (print-level nil))
                 (widen)
@@ -1528,7 +1528,7 @@ the archive of the file moved to, creating it if it does not exist."
             ;; Delete the category from the old file, and if that was the
             ;; last category, delete the file.  Also handle archive file
             ;; if necessary.
-            (let ((buffer-read-only nil))
+            (let ((inhibit-read-only t))
               (widen)
               (remove-overlays beg end)
               (delete-region beg end)
@@ -1581,7 +1581,7 @@ archive file and the source category is deleted."
          here)
     (with-current-buffer (get-buffer (find-file-noselect tfile))
       (widen)
-      (let* ((buffer-read-only nil)
+      (let* ((inhibit-read-only t)
              (cbeg (progn
                      (re-search-backward
                       (concat "^" (regexp-quote todo-category-beg)) nil t)
@@ -1609,7 +1609,7 @@ archive file and the source category is deleted."
           (unless (derived-mode-p 'todo-mode) (todo-mode))
           (widen)
           (goto-char (point-min))
-          (let ((buffer-read-only nil))
+          (let ((inhibit-read-only t))
             ;; Merge any todo items.
             (unless (zerop (length todo))
               (re-search-forward
@@ -1647,7 +1647,7 @@ archive file and the source category is deleted."
       (with-current-buffer (get-buffer (find-file-noselect tarchive))
         (widen)
         (goto-char (point-min))
-        (let* ((buffer-read-only nil)
+        (let* ((inhibit-read-only t)
                (cbeg (progn
                        (when (re-search-forward
                               (concat "^" (regexp-quote
@@ -1967,7 +1967,7 @@ their associated keys and their effects."
         (setq todo-current-todo-file file)
         (unless todo-global-current-todo-file
           (setq todo-global-current-todo-file todo-current-todo-file))
-        (let ((buffer-read-only nil)
+        (let ((inhibit-read-only t)
               done-only item-added)
           (unless copy
             (setq new-item
@@ -2197,9 +2197,9 @@ the item at point."
                                      end t)
                   (if comment-delete
                       (when (todo-y-or-n-p "Delete comment? ")
-                        (let ((buffer-read-only nil))
+                        (let ((inhibit-read-only t))
                           (delete-region (match-beginning 0) (match-end 0))))
-                    (let ((buffer-read-only nil))
+                    (let ((inhibit-read-only t))
                       (replace-match (save-match-data
                                        (prog1 (let ((buffer-read-only t))
                                                 (read-string
@@ -2216,7 +2216,7 @@ the item at point."
                                      nil nil nil 1)))
                 (if comment-delete
                     (user-error "There is no comment to delete")
-                  (let ((buffer-read-only nil))
+                  (let ((inhibit-read-only t))
                     (insert " [" todo-comment-string ": "
                             (prog1 (let ((buffer-read-only t))
                                      (read-string prompt))
@@ -2261,7 +2261,7 @@ the item at point."
                 (todo-category-number ocat)
                 (todo-category-select)
                 (goto-char opoint))
-              (let ((buffer-read-only nil))
+              (let ((inhibit-read-only t))
                 (todo-remove-item)
                 (todo-insert-with-overlays new))
               (move-to-column item-beg)))))))))
@@ -2493,8 +2493,8 @@ made in the number or names of categories."
                            (month month)
                            (day day)
                            (dayname nil)) ;; dayname
-                        (mapconcat #'eval calendar-date-display-form "")))))
-            (let ((buffer-read-only nil))
+                        (mapconcat #'eval calendar-date-display-form)))))
+            (let ((inhibit-read-only t))
               (when ndate (replace-match ndate nil nil nil 1))
               ;; Add new time string to the header, if it was supplied.
               (when ntime
@@ -2754,7 +2754,7 @@ meaning to raise or lower the item's priority by one."
             (when match
               (user-error (concat "Cannot reprioritize items from the same "
                                   "category in this mode, only in Todo mode")))))
-        (let ((buffer-read-only nil))
+        (let ((inhibit-read-only t))
           ;; Interactively or with non-nil ARG, relocate the item within its
           ;; category.
           (when (or arg (called-interactively-p 'any))
@@ -2877,7 +2877,7 @@ section in the category moved to."
                 (setq here (point))
                 (while todo-items
                   (todo-forward-item)
-                  (let ((buffer-read-only nil))
+                  (let ((inhibit-read-only t))
                     (todo-insert-with-overlays (pop todo-items)))))
               ;; Move done items en bloc to top of done items section.
               (when done-items
@@ -2892,7 +2892,7 @@ section in the category moved to."
                 (forward-line)
                 (unless here (setq here (point)))
                 (while done-items
-                  (let ((buffer-read-only nil))
+                  (let ((inhibit-read-only t))
                     (todo-insert-with-overlays (pop done-items)))
                   (todo-item-end)
                   (forward-line)))
@@ -2933,13 +2933,13 @@ section in the category moved to."
                         (goto-char beg)
                         (while (< (point) end)
                           (if (todo-marked-item-p)
-                              (let ((buffer-read-only nil))
+                              (let ((inhibit-read-only t))
                                 (todo-remove-item))
                             (todo-forward-item)))
                         (setq todo-categories-with-marks
                               (assq-delete-all cat1 todo-categories-with-marks)))
                     (if ov (delete-overlay ov))
-                    (let ((buffer-read-only nil))
+                    (let ((inhibit-read-only t))
                       (todo-remove-item)))))
               (when todo (todo-update-count 'todo (- todo) cat1))
               (when diary (todo-update-count 'diary (- diary) cat1))
@@ -2999,7 +2999,7 @@ visible."
              (show-done (save-excursion
                           (goto-char (point-min))
                           (re-search-forward todo-done-string-start nil t)))
-             (buffer-read-only nil)
+             (inhibit-read-only t)
              header item done-items
              (opoint (point)))
         ;; Don't add empty comment to done item.
@@ -3131,7 +3131,7 @@ comments without asking."
           (when ov (delete-overlay ov))
           (if (not undone)
               (goto-char opoint)
-            (let ((buffer-read-only nil))
+            (let ((inhibit-read-only t))
               (if marked
                   (progn
                     (setq item nil)
@@ -3299,7 +3299,7 @@ this category does not exist in the archive, it is created."
                   (todo-archive-mode))
                 (if headers-hidden (todo-toggle-item-header))))
             (with-current-buffer tbuf
-              (let ((buffer-read-only nil))
+              (let ((inhibit-read-only t))
                 (cond
                  (all
                   (save-excursion
@@ -3602,7 +3602,7 @@ decreasing or increasing its number."
                ;; Category's name and items counts list.
                (catcons (nth (1- curnum) todo-categories))
                (todo-categories (nconc head (list catcons) tail))
-               (buffer-read-only nil)
+               (inhibit-read-only t)
                newcats)
           (when lower (setq todo-categories (nreverse todo-categories)))
           (setq todo-categories (delete-dups todo-categories))
@@ -3823,8 +3823,7 @@ which is the value of the user option
                                 (cons todo-categories-diary-label 'diary)
                                 (cons todo-categories-done-label 'done)
                                 (cons todo-categories-archived-label
-                                      'archived)))
-                          "")
+                                      'archived))))
              " ") ; Make highlighting on last column look better.
      'face (if (and todo-skip-archived-categories
                     (zerop (todo-get-count 'todo cat))
@@ -3932,8 +3931,7 @@ which is the value of the user option
                (list (cons todo-categories-todo-label 0)
                      (cons todo-categories-diary-label 1)
                      (cons todo-categories-done-label 2)
-                     (cons todo-categories-archived-label 3)))
-             ""))
+                     (cons todo-categories-archived-label 3)))))
     ;; Put cursor on Category button initially.
     (if pt (goto-char pt))
     (setq buffer-read-only t)))
@@ -4758,7 +4756,7 @@ Helper function for `todo-convert-legacy-files'."
        (time (match-string 4))
        dayname)
     (replace-match "")
-    (insert (mapconcat #'eval calendar-date-display-form "")
+    (insert (mapconcat #'eval calendar-date-display-form)
             (when time (concat " " time)))))
 
 (defun todo-convert-legacy-files ()
@@ -5112,7 +5110,7 @@ With nil or omitted CATEGORY, default to the current category."
 
 (defun todo-update-categories-sexp ()
   "Update the `todo-categories' sexp at the top of the file."
-  (let ((buffer-read-only nil)
+  (let ((inhibit-read-only t)
         (print-length nil)
         (print-level nil))
     (save-excursion
@@ -6180,7 +6178,7 @@ number of the last the day of the month."
                (if (memq 'month calendar-date-display-form)
                    month
                  monthname)))
-      (mapconcat #'eval calendar-date-display-form ""))))
+      (mapconcat #'eval calendar-date-display-form))))
 
 (defun todo-read-dayname ()
   "Choose name of a day of the week with completion and return it."