Small rmail and rmailmm changes, many doc fixes.

* lisp/mail/rmail.el (rmail-file-coding-system): It's only ever used
in a boolean sense, so just make it a boolean, and fix the doc.
(rmail-show-mime-function, rmail-mime-feature)
(rmail-require-mime-maybe): Doc fixes.
(rmail-show-message-1): Check rmail-show-mime-function is non-nil.

* lisp/mail/rmailmm.el (rmail-show-mime): Doc fix.

3 files changed, 21 insertions, 17 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 95834e81a8d..91724c54e84 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,13 @@
+2011-11-15  Glenn Morris  <rgm@gnu.org>
+
+        * mail/rmail.el (rmail-file-coding-system): It's only ever used
+        in a boolean sense, so just make it a boolean, and fix the doc.
+        (rmail-show-mime-function, rmail-mime-feature)
+        (rmail-require-mime-maybe): Doc fixes.
+        (rmail-show-message-1): Check rmail-show-mime-function is non-nil.
+
+        * mail/rmailmm.el (rmail-show-mime): Doc fix.
+
 2011-11-15  Juanma Barranquero  <lekktu@gmail.com>
 
         * epg.el (epg-start-decrypt, epg-start-verify, epg-start-sign)
diff --git a/lisp/mail/rmail.el b/lisp/mail/rmail.el
index 4ecd1c2fd0d..d1322915aba 100644
--- a/lisp/mail/rmail.el
+++ b/lisp/mail/rmail.el
@@ -631,27 +631,20 @@ Element N specifies the summary line for message N+1.")
 This is set to nil by default.")
 
 (defcustom rmail-enable-mime t
-  "If non-nil, RMAIL uses MIME features.
-If the value is t, RMAIL automatically shows MIME decoded message.
-If the value is neither t nor nil, RMAIL does not show MIME decoded message
-until a user explicitly requires it.
-
-Even if the value is non-nil, you can't use MIME features
-unless the feature specified by `rmail-mime-feature' is available."
-  :type '(choice (const :tag "on" t)
-                 (const :tag "off" nil)
-                 (other :tag "when asked" ask))
+  "If non-nil, RMAIL automatically displays decoded MIME messages.
+For this to work, the feature specified by `rmail-mime-feature' must
+be available."
+  :type 'boolean
   :version "23.3"
   :group 'rmail)
 
 (defvar rmail-enable-mime-composing t
   "*If non-nil, RMAIL uses `rmail-insert-mime-forwarded-message-function' to forward.")
 
-;; FIXME unused.
 (defvar rmail-show-mime-function nil
-  "Function to show MIME decoded message of RMAIL file.
+  "Function of no argument called to show a decoded MIME message.
 This function is called when `rmail-enable-mime' is non-nil.
-It is called with no argument.")
+The package providing MIME support should set this.")
 
 ;;;###autoload
 (defvar rmail-insert-mime-forwarded-message-function nil
@@ -687,7 +680,7 @@ where MSG is the message number, REGEXP is the regular
 expression, LIMIT is the position specifying the end of header.")
 
 (defvar rmail-mime-feature 'rmailmm
-  "Feature to require to load MIME support in Rmail.
+  "Feature to require for MIME support in Rmail.
 When starting Rmail, if `rmail-enable-mime' is non-nil,
 this feature is required with `require'.
 
@@ -837,10 +830,10 @@ isn't provided."
        (display-warning
         'rmail
         (format "Although MIME support is requested
-by setting `rmail-enable-mime' to non-nil, the required feature
+through `rmail-enable-mime' being non-nil, the required feature
 `%s' (the value of `rmail-mime-feature')
 is not available in the current session.
-So, the MIME support is turned off for the moment."
+So, MIME support is turned off for the moment."
                 rmail-mime-feature)
         :warning)
        (setq rmail-enable-mime nil)))))
@@ -2700,6 +2693,7 @@ The current mail message becomes the message displayed."
           ;; inspect this value to determine how to toggle.
           (set (make-local-variable 'rmail-header-style) header-style))
         (if (and rmail-enable-mime
+                 rmail-show-mime-function
                  (re-search-forward "mime-version: 1.0" nil t))
             (let ((rmail-buffer mbox-buf)
                   (rmail-view-buffer view-buf))
diff --git a/lisp/mail/rmailmm.el b/lisp/mail/rmailmm.el
index 45f7fe24f26..46cd4bbfb37 100644
--- a/lisp/mail/rmailmm.el
+++ b/lisp/mail/rmailmm.el
@@ -1319,7 +1319,7 @@ attachments as specified by `rmail-mime-attachment-dirs-alist'."
          message type disposition encoding))
 
 (defun rmail-show-mime ()
-  "Function to set in `rmail-show-mime-function' (which see)."
+  "Function to use for the value of `rmail-show-mime-function'."
   (let ((entity (rmail-mime-parse))
         (rmail-mime-mbox-buffer rmail-buffer)
         (rmail-mime-view-buffer rmail-view-buffer)