bug#9820: 24.0.90; Behaviour of add-file-local-variable

[Juri Linkov]

> But please eliminate this code duplication.

Code duplication is eliminated by adding a new function
`modify-file-local-variable-message' that now also performs
more checks to decide when to display the message:

=== modified file 'lisp/files-x.el'
--- lisp/files-x.el     2013-06-15 22:44:38 +0000
+++ lisp/files-x.el     2013-06-17 22:34:33 +0000
@@ -115,7 +115,38 @@ (defun read-file-local-variable-mode ()
      ((and (stringp mode) (fboundp (intern mode))) (intern mode))
      (t mode))))
 
-(defun modify-file-local-variable (variable value op)
+(defun modify-file-local-variable-message (variable value op)
+  (let* ((not-value (make-symbol ""))
+        (old-value (cond ((eq variable 'mode)
+                          major-mode)
+                         ((eq variable 'coding)
+                          buffer-file-coding-system)
+                         (t (if (and (symbolp variable)
+                                     (boundp variable))
+                                (symbol-value variable)
+                              not-value))))
+        (new-value (if (eq op 'delete)
+                       (cond ((eq variable 'mode)
+                              (default-value 'major-mode))
+                             ((eq variable 'coding)
+                              (default-value 'buffer-file-coding-system))
+                             (t (if (and (symbolp variable)
+                                         (default-boundp variable))
+                                    (default-value variable)
+                                  not-value)))
+                     (cond ((eq variable 'mode)
+                            (let ((string (format "%S" value)))
+                              (if (string-match-p "-mode\\'" string)
+                                  value
+                                (intern (concat string "-mode")))))
+                           (t value)))))
+    (when (or (eq old-value not-value)
+             (eq new-value not-value)
+             (not (equal old-value new-value)))
+      (message "%s" (substitute-command-keys
+                    "For this change to take effect revisit file using 
\\[revert-buffer]")))))
+
+(defun modify-file-local-variable (variable value op &optional interactive)
   "Modify file-local VARIABLE in Local Variables depending on operation OP.
 
 If OP is `add-or-replace' then delete all existing settings of
@@ -198,10 +229,13 @@ (defun modify-file-local-variable (varia
           ((eq variable 'mode) (goto-char beg))
           ((null replaced-pos) (goto-char end))
           (replaced-pos (goto-char replaced-pos)))
-         (insert (format "%s%S: %S%s\n" prefix variable value suffix)))))))
+         (insert (format "%s%S: %S%s\n" prefix variable value suffix))))
+
+      (when interactive
+       (modify-file-local-variable-message variable value op)))))
 
 ;;;###autoload
-(defun add-file-local-variable (variable value)
+(defun add-file-local-variable (variable value &optional interactive)
   "Add file-local VARIABLE with its VALUE to the Local Variables list.
 
 This command deletes all existing settings of VARIABLE (except `mode'
@@ -213,17 +247,17 @@ (defun add-file-local-variable (variable
 `Local Variables:' and the last line containing the string `End:'."
   (interactive
    (let ((variable (read-file-local-variable "Add file-local variable")))
-     (list variable (read-file-local-variable-value variable))))
-  (modify-file-local-variable variable value 'add-or-replace))
+     (list variable (read-file-local-variable-value variable) t)))
+  (modify-file-local-variable variable value 'add-or-replace interactive))
 
 ;;;###autoload
-(defun delete-file-local-variable (variable)
+(defun delete-file-local-variable (variable &optional interactive)
   "Delete all settings of file-local VARIABLE from the Local Variables list."
   (interactive
-   (list (read-file-local-variable "Delete file-local variable")))
-  (modify-file-local-variable variable nil 'delete))
+   (list (read-file-local-variable "Delete file-local variable") t))
+  (modify-file-local-variable variable nil 'delete interactive))
 
-(defun modify-file-local-variable-prop-line (variable value op)
+(defun modify-file-local-variable-prop-line (variable value op &optional 
interactive)
   "Modify file-local VARIABLE in the -*- line depending on operation OP.
 
 If OP is `add-or-replace' then delete all existing settings of
@@ -337,10 +371,13 @@ (defun modify-file-local-variable-prop-l
              (insert ";"))
          (unless (eq (char-before) ?\s) (insert " "))
          (insert (format "%S: %S;" variable value))
-         (unless (eq (char-after) ?\s) (insert " "))))))))
+         (unless (eq (char-after) ?\s) (insert " ")))))
+
+      (when interactive
+       (modify-file-local-variable-message variable value op)))))
 
 ;;;###autoload
-(defun add-file-local-variable-prop-line (variable value)
+(defun add-file-local-variable-prop-line (variable value &optional interactive)
   "Add file-local VARIABLE with its VALUE to the -*- line.
 
 This command deletes all existing settings of VARIABLE (except `mode'
@@ -355,15 +394,15 @@ (defun add-file-local-variable-prop-line
 then this function adds it."
   (interactive
    (let ((variable (read-file-local-variable "Add -*- file-local variable")))
-     (list variable (read-file-local-variable-value variable))))
-  (modify-file-local-variable-prop-line variable value 'add-or-replace))
+     (list variable (read-file-local-variable-value variable) t)))
+  (modify-file-local-variable-prop-line variable value 'add-or-replace 
interactive))
 
 ;;;###autoload
-(defun delete-file-local-variable-prop-line (variable)
+(defun delete-file-local-variable-prop-line (variable &optional interactive)
   "Delete all settings of file-local VARIABLE from the -*- line."
   (interactive
-   (list (read-file-local-variable "Delete -*- file-local variable")))
-  (modify-file-local-variable-prop-line variable nil 'delete))
+   (list (read-file-local-variable "Delete -*- file-local variable") t))
+  (modify-file-local-variable-prop-line variable nil 'delete interactive))
 
 (defvar auto-insert) ; from autoinsert.el