* lisp/newcomment.el (comment-styles): Add docs to each style.

Improve docstring.
(comment-style): Use comment-styles's docs to describe values.

Fixes: debbugs:7509

2 files changed, 59 insertions, 13 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 4ed0393594e..23d6130f2cb 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2010-12-03  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * newcomment.el (comment-styles): Add docs to each style (bug#7509).
+        Improve docstring.
+        (comment-style): Use comment-styles's docs to describe values.
+
 2010-12-03  Jan Djärv  <jan.h.d@swipnet.se>
 
         * term/common-win.el (x-setup-function-keys): Restore ns-new-frame
@@ -295,7 +301,7 @@
 
         * shell.el (shell): Use current-buffer by default if it's already
         a shell mode buffer and its process is dead.
-        Suggested by <jemarch@gnu.org>.
+        Suggested by Jose E. Marchesi <jemarch@gnu.org>.
 
 2010-11-23  Tassilo Horn  <tassilo@member.fsf.org>
 
diff --git a/lisp/newcomment.el b/lisp/newcomment.el
index de6b2474e21..3227d2ac539 100644
--- a/lisp/newcomment.el
+++ b/lisp/newcomment.el
@@ -187,21 +187,58 @@ This should generally stay 0, except for a few modes like Lisp where
 it is 1 so that regions are commented with two or three semi-colons.")
 
 (defconst comment-styles
-  '((plain      . (nil nil nil nil))
-    (indent     . (nil nil nil t))
-    (indent-or-triple
-                . (nil nil nil multi-char))
-    (aligned    . (nil t nil t))
-    (multi-line . (t nil nil t))
-    (extra-line . (t nil t t))
-    (box        . (nil t t t))
-    (box-multi  . (t t t t)))
-  "Comment region styles of the form (STYLE . (MULTI ALIGN EXTRA INDENT)).
+  '((plain      nil nil nil nil
+                "Start in column 0 (do not indent), as in Emacs-20")
+    (indent-or-triple nil nil nil multi-char
+              "Start in column 0, but only for single-char starters")
+    (indent     nil nil nil t
+                "Full comment per line, ends not aligned")
+    (aligned    nil t   nil t
+                "Full comment per line, ends aligned")
+    (box        nil t   t   t
+                "Full comment per line, ends aligned, + top and bottom")
+    (extra-line t   nil t   t
+                "One comment for all lines, end on a line by itself")
+    (multi-line t   nil nil t
+                "One comment for all lines, end on last commented line")
+    (box-multi  t   t   t   t
+                "One comment for all lines, + top and bottom"))
+  "Comment region style definitions.
+Each style is defined with a form (STYLE . (MULTI ALIGN EXTRA INDENT DOC)).
+DOC should succinctly describe the style.
 STYLE should be a mnemonic symbol.
 MULTI specifies that comments are allowed to span multiple lines.
+  e.g. in C it comments regions as
+     /* blabla
+      * bli */
+  rather than
+     /* blabla */
+     /* bli */
+  if `comment-end' is empty, this has no effect.
+
 ALIGN specifies that the `comment-end' markers should be aligned.
+  e.g. in C it comments regions as
+     /* blabla */
+     /* bli    */
+  rather than
+     /* blabla */
+     /* bli */
+  if `comment-end' is empty, this has no effect, unless EXTRA is also set,
+  in which case the comment gets wrapped in a box.
+  
 EXTRA specifies that an extra line should be used before and after the
   region to comment (to put the `comment-end' and `comment-start').
+  e.g. in C it comments regions as
+     /*
+      * blabla
+      * bli
+      */
+  rather than
+     /* blabla
+      * bli */
+  if the comment style is not multi line, this has no effect, unless ALIGN
+  is also set, in which case the comment gets wrapped in a box.
+
 INDENT specifies that the `comment-start' markers should not be put at the
   left margin but at the current indentation of the region to comment.
 If INDENT is `multi-char', that means indent multi-character
@@ -212,8 +249,11 @@ If INDENT is `multi-char', that means indent multi-character
   "Style to be used for `comment-region'.
 See `comment-styles' for a list of available styles."
   :type (if (boundp 'comment-styles)
-            `(choice ,@(mapcar (lambda (s) `(const ,(car s)))
-                               comment-styles))
+            `(choice
+              ,@(mapcar (lambda (s)
+                          `(const :tag ,(format "%s: %s" (car s) (nth 5 s))
+                                  ,(car s)))
+                        comment-styles))
           'symbol)
   :version "23.1"
   :group 'comment)