Add the ability to exclude dir-locals from subdirs. (Bug#8100)

* lisp/files.el (dir-locals-collect-variables):
Add the ability to exclude subdirectories.

* doc/emacs/custom.texi (Directory Variables):
Give an example of excluding subdirectories.

* doc/lispref/variables.texi (Directory Local Variables):
Mention `(subdirs . nil)' alist element.

* etc/NEWS: Mention this addition.

* lisp/dired-x.el (dired-omit-here-always): Add `(subdirs . nil)' to locals.

3 files changed, 24 insertions, 3 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index e5abd0b93d7..5b8a5be8280 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,10 @@
+2011-03-01  Glenn Morris  <rgm@gnu.org>
+
+        * files.el (dir-locals-collect-variables):
+        Add the ability to exclude subdirectories.  (Bug#8100)
+
+        * dired-x.el (dired-omit-here-always): Add `(subdirs . nil)' to locals.
+
 2011-02-28  Christoph Scholtes  <cschol2112@googlemail.com>
 
         * ido.el (ido-everywhere): Doc fix.
diff --git a/lisp/dired-x.el b/lisp/dired-x.el
index 816beb0034c..9941c7a0db5 100644
--- a/lisp/dired-x.el
+++ b/lisp/dired-x.el
@@ -786,6 +786,7 @@ See also `dired-enable-local-variables'."
                'hack-dir-local-variables-non-file-buffer "24.1")
 
 ;; Not sure this is worth having a dedicated command for...
+;; See the more general features in files-x.el.
 (defun dired-omit-here-always ()
   "Create `dir-locals-file' setting `dired-omit-mode' to t in `dired-mode'.
 If in a Dired buffer, reverts it."
@@ -798,7 +799,9 @@ replace it with a dir-locals-file `./%s'"
   (if (file-exists-p dir-locals-file)
       (message "File `./%s' already exists." dir-locals-file)
     (with-temp-buffer
-      (insert "((dired-mode . ((dired-omit-mode . t))))\n")
+      (insert "\
+\((dired-mode . ((subdirs . nil)
+                (dired-omit-mode . t))))\n")
       (write-file dir-locals-file))
     ;; Run extra-hooks and revert directory.
     (when (derived-mode-p 'dired-mode)
diff --git a/lisp/files.el b/lisp/files.el
index 5890bf9b8c9..bafae814756 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -3394,8 +3394,19 @@ Return the new variables list."
                                  (cdr entry) root variables))))
              ((or (not key)
                   (derived-mode-p key))
-              (setq variables (dir-locals-collect-mode-variables
-                               (cdr entry) variables))))))
+              (let* ((alist (cdr entry))
+                     (subdirs (assq 'subdirs alist)))
+                (if (or (not subdirs)
+                        (progn
+                          (setq alist (delq subdirs alist))
+                          (cdr-safe subdirs))
+                        ;; TODO someone might want to extent this to allow
+                        ;; integer values for subdir, where N means
+                        ;; variables apply to this directory and N levels
+                        ;; below it (0 == nil).
+                        (equal root default-directory))
+                    (setq variables (dir-locals-collect-mode-variables
+                                     alist variables))))))))
       (error
        ;; The file's content might be invalid (e.g. have a merge conflict), but
        ;; that shouldn't prevent the user from opening the file.