(define-derived-mode, derived-mode-make-docstring): Allow `parent' to be nil.

1 files changed, 28 insertions, 22 deletions

diff --git a/lisp/derived.el b/lisp/derived.el
index 28b1a99bd27..9512bae492f 100644
--- a/lisp/derived.el
+++ b/lisp/derived.el
@@ -100,7 +100,8 @@
 The arguments to this command are as follow:
 
 CHILD:     the name of the command for the derived mode.
-PARENT:    the name of the command for the parent mode (e.g. `text-mode').
+PARENT:    the name of the command for the parent mode (e.g. `text-mode')
+           or nil if there is no parent.
 NAME:      a string which will appear in the status line (e.g. \"Hypertext\")
 DOCSTRING: an optional documentation string--if you do not supply one,
            the function will attempt to invent something useful.
@@ -131,7 +132,7 @@ been generated automatically, with a reference to the keymap."
     (push docstring body)
     (setq docstring nil))
 
-  (unless parent (setq parent 'fundamental-mode))
+  (when (eq parent 'fundamental-mode) (setq parent nil))
 
   (let ((map (derived-mode-map-name child))
         (syntax (derived-mode-syntax-table-name child))
@@ -141,7 +142,7 @@ been generated automatically, with a reference to the keymap."
          
     `(progn
        (defvar ,map (make-sparse-keymap))
-       (defvar ,syntax (make-char-table 'syntax-table nil))
+       (defvar ,syntax (make-syntax-table))
        (defvar ,abbrev)
        (define-abbrev-table ',abbrev nil)
        (put ',child 'derived-mode-parent ',parent)
@@ -152,26 +153,28 @@ been generated automatically, with a reference to the keymap."
                                         ; Run the parent.
          ;; (combine-run-hooks
 
-          (,parent)
-                                        ; Identify special modes.
-          (if (get (quote ,parent) 'special)
-              (put (quote ,child) 'special t))
+          (,(or parent 'kill-all-local-variables))
                                         ; Identify the child mode.
           (setq major-mode (quote ,child))
           (setq mode-name ,name)
+                                        ; Identify special modes.
+          ,(when parent
+             `(progn
+                (if (get (quote ,parent) 'special)
+                    (put (quote ,child) 'special t))
                                         ; Set up maps and tables.
-          (unless (keymap-parent ,map)
-            (set-keymap-parent ,map (current-local-map)))
-          (let ((parent (char-table-parent ,syntax)))
-            (unless (and parent (not (eq parent (standard-syntax-table))))
-              (set-char-table-parent ,syntax (syntax-table))))
-          (when local-abbrev-table
-            (mapatoms
-             (lambda (symbol)
-               (or (intern-soft (symbol-name symbol) ,abbrev)
-                   (define-abbrev ,abbrev (symbol-name symbol)
-                     (symbol-value symbol) (symbol-function symbol))))
-             local-abbrev-table))
+                (unless (keymap-parent ,map)
+                  (set-keymap-parent ,map (current-local-map)))
+                (let ((parent (char-table-parent ,syntax)))
+                  (unless (and parent (not (eq parent (standard-syntax-table))))
+                    (set-char-table-parent ,syntax (syntax-table))))
+                (when local-abbrev-table
+                  (mapatoms
+                   (lambda (symbol)
+                     (or (intern-soft (symbol-name symbol) ,abbrev)
+                         (define-abbrev ,abbrev (symbol-name symbol)
+                           (symbol-value symbol) (symbol-function symbol))))
+                   local-abbrev-table))))
        
           (use-local-map ,map)
           (set-syntax-table ,syntax)
@@ -234,20 +237,23 @@ this function is not very useful.  Use `derived-mode-p' instead."
     (unless (stringp docstring)
       ;; Use a default docstring.
       (setq docstring
-            (format "Major mode derived from `%s' by `define-derived-mode'.
+            (if (null parent)
+                (format "Major-mode.
+Uses keymap `%s', abbrev table `%s' and syntax-table `%s'." map abbrev syntax)
+              (format "Major mode derived from `%s' by `define-derived-mode'.
 It inherits all of the parent's attributes, but has its own keymap,
 abbrev table and syntax table:
 
   `%s', `%s' and `%s'
 
 which more-or-less shadow %s's corresponding tables."
-                    parent map abbrev syntax parent)))
+                      parent map abbrev syntax parent))))
   
     (unless (string-match (regexp-quote (symbol-name hook)) docstring)
       ;; Make sure the docstring mentions the mode's hook
       (setq docstring
             (concat docstring
-                    (if (eq parent 'fundamental-mode)
+                    (if (null parent)
                         "\n\nThis mode "
                       (concat
                        "\n\nIn addition to any hooks its parent mode "