bug#33263: 27.0.50; Tidying up Gnus modes

[Eric Abrahamsen <eric@ericabrahamsen.net>]

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The attached patch does a couple of things to clean up Gnus's various
major modes:

- Creates a do-nothing `gnus-mode', derived from `special-mode', to
  serve as parent mode for all the other major modes. This isn't so
  important, but sometimes it would be nice to do (derived-mode-p
  'gnus-mode).
- Derives everything from `gnus-mode', and turns a couple of modes from
  functions that manually set up modes into proper calls to
  `define-derived-mode'.
- Removes code like "(setq buffer-read-only t)", as that's automatically
  done by `special-mode'.
- Where appropriate, deletes custom definitions for gnus-*-mode-hook, as
  these hooks are already automatically created by the define-mode
  calls. (Maybe this removal isn't worth doing?)

This patch probably needs more testing, but I'm floating it first for
any comments.

Eric

In GNU Emacs 27.0.50 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.1)
 of 2018-10-31 built on slip

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From 395babb983e466d21928433c18faddedf3d88e8f Mon Sep 17 00:00:00 2001
From: Eric Abrahamsen <eric@ericabrahamsen.net>
Date: Mon, 25 Jun 2018 17:40:19 -0700
Subject: [PATCH] Provide new gnus-mode, derive all gnus major modes from this

* lisp/gnus/gnus.el (gnus-mode): New do-nothing major mode, derived
  from special mode.
* lisp/gnus/gnus-sum.el (gnus-summary-mode): Change from a function to
  a major mode, derive from gnus-mode.
  (gnus-summary-setup-buffer): Change call a bit -- can no longer pass
  an argument to the mode function.
* lisp/gnus/gnus-srvr.el (gnus-browse-mode): Derive from gnus-mode.
  (gnus-server-setup-buffer): Remove unnecessary function.
  (gnus-enter-server-buffer): Call gnus-server-mode here, and call it
  whether the server buffer already existed or not.
  (gnus-server-mode): Change from a function to a major mode.
  (gnus-server-mode-hook): Delete custom option, this is automatically
  created.
* lisp/gnus/gnus-salt.el (gnus-tree-mode): Derive from gnus-mode.
  (gnus-tree-mode-hook): Delete custom option, this is automatically
  created.
* lisp/gnus/gnus-kill.el (gnus-kill-file-mode-hook): Delete custom
  option.
* lisp/gnus/gnus-group.el (gnus-group-mode):
* lisp/gnus/gnus-art.el (gnus-article-mode):
* lisp/gnus/gnus-agent.el (gnus-category-mode): Derive from gnus-mode.
  (gnus-category-mode-hook): Delete custom option.
---
 lisp/gnus/gnus-agent.el | 10 ++-------
 lisp/gnus/gnus-art.el   |  8 ++-----
 lisp/gnus/gnus-group.el |  8 ++-----
 lisp/gnus/gnus-kill.el  |  5 -----
 lisp/gnus/gnus-salt.el  |  9 +-------
 lisp/gnus/gnus-srvr.el  | 46 +++++++++--------------------------------
 lisp/gnus/gnus-sum.el   | 20 ++++--------------
 lisp/gnus/gnus.el       |  6 ++++++
 8 files changed, 27 insertions(+), 85 deletions(-)

diff --git a/lisp/gnus/gnus-agent.el b/lisp/gnus/gnus-agent.el
index 18e6174fa0..93a675584f 100644
--- a/lisp/gnus/gnus-agent.el
+++ b/lisp/gnus/gnus-agent.el
@@ -2575,9 +2575,6 @@ gnus-agent-fetch-group-1
 ;;; Agent Category Mode
 ;;;
 
-(defvar gnus-category-mode-hook nil
-  "Hook run in `gnus-category-mode' buffers.")
-
 (defvar gnus-category-line-format "     %(%20c%): %g\n"
   "Format of category lines.
 
@@ -2613,7 +2610,6 @@ gnus-category-line-format-spec
 (defvar gnus-category-mode-line-format-spec nil)
 
 (defvar gnus-category-mode-map nil)
-(put 'gnus-category-mode 'mode-class 'special)
 
 (unless gnus-category-mode-map
   (setq gnus-category-mode-map (make-sparse-keymap))
@@ -2655,9 +2651,8 @@ gnus-category-make-menu-bar
 
     (gnus-run-hooks 'gnus-category-menu-hook)))
 
-(define-derived-mode gnus-category-mode fundamental-mode "Category"
+(define-derived-mode gnus-category-mode gnus-mode "Category"
   "Major mode for listing and editing agent categories.
-
 All normal editing commands are switched off.
 \\<gnus-category-mode-map>
 For more in-depth information on this mode, read the manual
@@ -2672,8 +2667,7 @@ gnus-category-mode
   (gnus-set-default-directory)
   (setq mode-line-process nil)
   (buffer-disable-undo)
-  (setq truncate-lines t)
-  (setq buffer-read-only t))
+  (setq truncate-lines t))
 
 (defalias 'gnus-category-position-point 'gnus-goto-colon)
 
diff --git a/lisp/gnus/gnus-art.el b/lisp/gnus/gnus-art.el
index f28e6db3c7..c78bb3325f 100644
--- a/lisp/gnus/gnus-art.el
+++ b/lisp/gnus/gnus-art.el
@@ -4388,8 +4388,6 @@ article-verify-cancel-lock
 ;;; Gnus article mode
 ;;;
 
-(put 'gnus-article-mode 'mode-class 'special)
-
 (set-keymap-parent gnus-article-mode-map widget-keymap)
 
 (gnus-define-keys gnus-article-mode-map
@@ -4467,9 +4465,8 @@ gnus-article-make-menu-bar
 (defvar bookmark-make-record-function)
 (defvar shr-put-image-function)
 
-(define-derived-mode gnus-article-mode fundamental-mode "Article"
+(define-derived-mode gnus-article-mode gnus-mode "Article"
   "Major mode for displaying an article.
-
 All normal editing commands are switched off.
 
 The following commands are available in addition to all summary mode
@@ -4510,8 +4507,7 @@ gnus-article-mode
     (setq cursor-in-non-selected-windows nil))
   (gnus-set-default-directory)
   (buffer-disable-undo)
-  (setq buffer-read-only t
-	show-trailing-whitespace nil)
+  (setq show-trailing-whitespace nil)
   (mm-enable-multibyte))
 
 (defun gnus-article-setup-buffer ()
diff --git a/lisp/gnus/gnus-group.el b/lisp/gnus/gnus-group.el
index 6af27afbfa..d526894b3a 100644
--- a/lisp/gnus/gnus-group.el
+++ b/lisp/gnus/gnus-group.el
@@ -567,8 +567,6 @@ gnus-group-list-option
 ;;; Gnus group mode
 ;;;
 
-(put 'gnus-group-mode 'mode-class 'special)
-
 (gnus-define-keys gnus-group-mode-map
   " " gnus-group-read-group
   "=" gnus-group-select-group
@@ -1106,9 +1104,8 @@ gnus-group-make-tool-bar
 	  (set (make-local-variable 'tool-bar-map) map))))
   gnus-group-tool-bar-map)
 
-(define-derived-mode gnus-group-mode fundamental-mode "Group"
+(define-derived-mode gnus-group-mode gnus-mode "Group"
   "Major mode for reading news.
-
 All normal editing commands are switched off.
 \\<gnus-group-mode-map>
 The group buffer lists (some of) the groups available.  For instance,
@@ -1131,8 +1128,7 @@ gnus-group-mode
   (setq mode-line-process nil)
   (buffer-disable-undo)
   (setq truncate-lines t)
-  (setq buffer-read-only t
-	show-trailing-whitespace nil)
+  (setq show-trailing-whitespace nil)
   (gnus-set-default-directory)
   (gnus-update-format-specifications nil 'group 'group-mode)
   (gnus-update-group-mark-positions)
diff --git a/lisp/gnus/gnus-kill.el b/lisp/gnus/gnus-kill.el
index 60732c11d5..e65ff51ce7 100644
--- a/lisp/gnus/gnus-kill.el
+++ b/lisp/gnus/gnus-kill.el
@@ -29,11 +29,6 @@
 (require 'gnus-art)
 (require 'gnus-range)
 
-(defcustom gnus-kill-file-mode-hook nil
-  "Hook for Gnus kill file mode."
-  :group 'gnus-score-kill
-  :type 'hook)
-
 (defcustom gnus-kill-expiry-days 7
   "Number of days before expiring unused kill file entries."
   :group 'gnus-score-kill
diff --git a/lisp/gnus/gnus-salt.el b/lisp/gnus/gnus-salt.el
index aff841760a..0504465de3 100644
--- a/lisp/gnus/gnus-salt.el
+++ b/lisp/gnus/gnus-salt.el
@@ -396,11 +396,6 @@ gnus-generate-tree-function
 		(function :tag "Other" nil))
   :group 'gnus-summary-tree)
 
-(defcustom gnus-tree-mode-hook nil
-  "Hook run in tree mode buffers."
-  :type 'hook
-  :group 'gnus-summary-tree)
-
 ;;; Internal variables.
 
 (defvar gnus-tmp-name)
@@ -445,8 +440,6 @@ gnus-tree-mode-map
      'undefined 'gnus-tree-read-summary-keys map)
     map))
 
-(put 'gnus-tree-mode 'mode-class 'special)
-
 (defun gnus-tree-make-menu-bar ()
   (unless (boundp 'gnus-tree-menu)
     (easy-menu-define
@@ -454,7 +447,7 @@ gnus-tree-make-menu-bar
       '("Tree"
 	["Select article" gnus-tree-select-article t]))))
 
-(define-derived-mode gnus-tree-mode fundamental-mode "Tree"
+(define-derived-mode gnus-tree-mode gnus-mode "Tree"
   "Major mode for displaying thread trees."
   (gnus-set-format 'tree-mode)
   (gnus-set-format 'tree t)
diff --git a/lisp/gnus/gnus-srvr.el b/lisp/gnus/gnus-srvr.el
index dfca5e9d2c..03718fd104 100644
--- a/lisp/gnus/gnus-srvr.el
+++ b/lisp/gnus/gnus-srvr.el
@@ -36,11 +36,6 @@
 
 (autoload 'gnus-group-make-nnir-group "nnir")
 
-(defcustom gnus-server-mode-hook nil
-  "Hook run in `gnus-server-mode' buffers."
-  :group 'gnus-server
-  :type 'hook)
-
 (defcustom gnus-server-exit-hook nil
   "Hook run when exiting the server buffer."
   :group 'gnus-server
@@ -108,7 +103,7 @@ gnus-server-line-format-spec
 (defvar gnus-server-mode-line-format-spec nil)
 (defvar gnus-server-killed-servers nil)
 
-(defvar gnus-server-mode-map)
+(defvar gnus-server-mode-map nil)
 
 (defcustom gnus-server-menu-hook nil
   "Hook run after the creation of the server mode menu."
@@ -150,11 +145,8 @@ gnus-server-make-menu-bar
 
     (gnus-run-hooks 'gnus-server-menu-hook)))
 
-(defvar gnus-server-mode-map nil)
-(put 'gnus-server-mode 'mode-class 'special)
-
 (unless gnus-server-mode-map
-  (setq gnus-server-mode-map (make-sparse-keymap))
+  (setq gnus-server-mode-map (make-keymap))
   (suppress-keymap gnus-server-mode-map)
 
   (gnus-define-keys gnus-server-mode-map
@@ -253,9 +245,8 @@ gnus-server-font-lock-keywords
     ("(\\(offline\\))" 1 'gnus-server-offline)
     ("(\\(denied\\))" 1 'gnus-server-denied)))
 
-(defun gnus-server-mode ()
+(define-derived-mode gnus-server-mode gnus-mode "Server"
   "Major mode for listing and editing servers.
-
 All normal editing commands are switched off.
 \\<gnus-server-mode-map>
 For more in-depth information on this mode, read the manual
@@ -264,23 +255,16 @@ gnus-server-mode
 The following commands are available:
 
 \\{gnus-server-mode-map}"
-  ;; FIXME: Use define-derived-mode.
-  (interactive)
   (when (gnus-visual-p 'server-menu 'menu)
     (gnus-server-make-menu-bar))
-  (kill-all-local-variables)
   (gnus-simplify-mode-line)
-  (setq major-mode 'gnus-server-mode)
-  (setq mode-name "Server")
   (gnus-set-default-directory)
   (setq mode-line-process nil)
-  (use-local-map gnus-server-mode-map)
   (buffer-disable-undo)
   (setq truncate-lines t)
-  (setq buffer-read-only t)
   (set (make-local-variable 'font-lock-defaults)
-       '(gnus-server-font-lock-keywords t))
-  (gnus-run-mode-hooks 'gnus-server-mode-hook))
+       '(gnus-server-font-lock-keywords t)))
+
 
 (defun gnus-server-insert-server-line (name method)
   (let* ((gnus-tmp-name name)
@@ -320,21 +304,15 @@ gnus-server-insert-server-line
 
 (defun gnus-enter-server-buffer ()
   "Set up the server buffer."
-  (gnus-server-setup-buffer)
   (gnus-configure-windows 'server)
   ;; Usually `gnus-configure-windows' will finish with the
   ;; `gnus-server-buffer' selected as the current buffer, but not always (I
   ;; bumped into it when starting from a dedicated *Group* frame, and
   ;; gnus-configure-windows opened *Server* into its own dedicated frame).
   (with-current-buffer (get-buffer gnus-server-buffer)
+    (gnus-server-mode)
     (gnus-server-prepare)))
 
-(defun gnus-server-setup-buffer ()
-  "Initialize the server buffer."
-  (unless (get-buffer gnus-server-buffer)
-    (with-current-buffer (gnus-get-buffer-create gnus-server-buffer)
-      (gnus-server-mode))))
-
 (defun gnus-server-prepare ()
   (gnus-set-format 'server-mode)
   (gnus-set-format 'server t)
@@ -717,12 +695,10 @@ gnus-browse-subscribe-newsgroup-method
 		function
 		(repeat function)))
 
-(defvar gnus-browse-mode-hook nil)
-(defvar gnus-browse-mode-map nil)
-(put 'gnus-browse-mode 'mode-class 'special)
+(defvar gnus-browse-mode-map (make-keymap))
 
 (unless gnus-browse-mode-map
-  (setq gnus-browse-mode-map (make-keymap))
+  (defvar gnus-browse-mode-map (make-keymap))
   (suppress-keymap gnus-browse-mode-map)
 
   (gnus-define-keys
@@ -897,9 +873,8 @@ gnus-browse-foreign-server
       (gnus-message 5 "Connecting to %s...done" (nth 1 method))
       t))))
 
-(define-derived-mode gnus-browse-mode fundamental-mode "Browse Server"
+(define-derived-mode gnus-browse-mode gnus-mode "Browse Server"
   "Major mode for browsing a foreign server.
-
 All normal editing commands are switched off.
 
 \\<gnus-browse-mode-map>
@@ -918,8 +893,7 @@ gnus-browse-mode
   (setq mode-line-process nil)
   (buffer-disable-undo)
   (setq truncate-lines t)
-  (gnus-set-default-directory)
-  (setq buffer-read-only t))
+  (gnus-set-default-directory))
 
 (defun gnus-browse-read-group (&optional no-article number)
   "Enter the group at the current line.
diff --git a/lisp/gnus/gnus-sum.el b/lisp/gnus/gnus-sum.el
index f9fae3792b..67abf6d640 100644
--- a/lisp/gnus/gnus-sum.el
+++ b/lisp/gnus/gnus-sum.el
@@ -1842,8 +1842,6 @@ gnus-summary-bubble-group
 ;;; Gnus summary mode
 ;;;
 
-(put 'gnus-summary-mode 'mode-class 'special)
-
 (defvar gnus-article-commands-menu)
 
 ;; Non-orthogonal keys
@@ -3052,10 +3050,8 @@ bookmark-make-record-function
 \f
 (defvar bidi-paragraph-direction)
 
-(defun gnus-summary-mode (&optional group)
+(define-derived-mode gnus-summary-mode gnus-mode "Summary"
   "Major mode for reading articles.
-
-All normal editing commands are switched off.
 \\<gnus-summary-mode-map>
 Each line in this buffer represents one article.  To read an
 article, you can, for instance, type `\\[gnus-summary-next-page]'.  To move forwards
@@ -3072,24 +3068,16 @@ gnus-summary-mode
 The following commands are available:
 
 \\{gnus-summary-mode-map}"
-  ;; FIXME: Use define-derived-mode.
-  (interactive)
-  (kill-all-local-variables)
   (let ((gnus-summary-local-variables gnus-newsgroup-variables))
     (gnus-summary-make-local-variables))
   (gnus-summary-make-local-variables)
-  (setq gnus-newsgroup-name group)
   (when (gnus-visual-p 'summary-menu 'menu)
     (gnus-summary-make-menu-bar)
     (gnus-summary-make-tool-bar))
   (gnus-make-thread-indent-array)
   (gnus-simplify-mode-line)
-  (setq major-mode 'gnus-summary-mode)
-  (setq mode-name "Summary")
-  (use-local-map gnus-summary-mode-map)
   (buffer-disable-undo)
-  (setq buffer-read-only t
-	show-trailing-whitespace nil
+  (setq show-trailing-whitespace nil
 	truncate-lines t
 	bidi-paragraph-direction 'left-to-right)
   (add-to-invisibility-spec '(gnus-sum . t))
@@ -3101,7 +3089,6 @@ gnus-summary-mode
   (make-local-variable 'gnus-summary-dummy-line-format-spec)
   (make-local-variable 'gnus-summary-mark-positions)
   (add-hook 'pre-command-hook 'gnus-set-global-variables nil t)
-  (gnus-run-mode-hooks 'gnus-summary-mode-hook)
   (turn-on-gnus-mailing-list-mode)
   (mm-enable-multibyte)
   (set (make-local-variable 'bookmark-make-record-function)
@@ -3493,7 +3480,8 @@ gnus-summary-setup-buffer
 	  (not gnus-newsgroup-prepared))
       (set-buffer (gnus-get-buffer-create buffer))
       (setq gnus-summary-buffer (current-buffer))
-      (gnus-summary-mode group)
+      (setq gnus-newsgroup-name group)
+      (gnus-summary-mode)
       (when (gnus-group-quit-config group)
 	(set (make-local-variable 'gnus-single-article-buffer) nil))
       (make-local-variable 'gnus-article-buffer)
diff --git a/lisp/gnus/gnus.el b/lisp/gnus/gnus.el
index 2786323f67..6c59b13574 100644
--- a/lisp/gnus/gnus.el
+++ b/lisp/gnus/gnus.el
@@ -637,6 +637,12 @@ gnus-summary-low-read
   "Face used for low interest read articles."
   :group 'gnus-summary)
 
+;;; Base gnus-mode
+
+(define-derived-mode gnus-mode special-mode nil
+  "Base mode from which all other gnus modes derive.
+This does nothing but derive from `special-mode', and should not
+be used directly.")
 
 ;;;
 ;;; Gnus buffers
-- 
2.19.1