[PATCH] org-ctags.el: Do not activate on load

[Max Nikulin <manikulin@gmail.com>]

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On 29/04/2024 20:12, Ihor Radchenko wrote:
> Max Nikulin writes:
>>
>> Notice that new tests for org-ctags do not require user interactions.
[...]
> Of course, the cause is the known side effect of loading org-ctags.
> 
> Maybe we can disable the tests until that bug is fixed.
> Or, ideally, load org-ctags only when the relevant tests are running and
> unload it after they finish.

Isn't it better to modify buggy org-ctags than to add various kludges to 
tests?

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From 0d260a0f260afb0f407d00b6a53ed2121a240203 Mon Sep 17 00:00:00 2001
From: Max Nikulin <manikulin@gmail.com>
Date: Mon, 29 Apr 2024 21:34:13 +0700
Subject: [PATCH 1/2] org-ctags.el: Define unload function
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

* lisp/org-ctags.el (org-ctags-unload-function): New function to cleanup
during `unload-feature' call.
(org-ctags--open-link-functions-list org-ctags-open-link-functions):
Define and use list of options available for `org-open-link-functions'.
(org-ctags--visit-tags-table): Give a name to remove the function from
`org-mode-hook' on library unload.

Prevent the following error after library unloading

    Symbol’s function definition is void: org-ctags-find-tag
---
 lisp/org-ctags.el | 60 +++++++++++++++++++++++++++++++----------------
 1 file changed, 40 insertions(+), 20 deletions(-)

diff --git a/lisp/org-ctags.el b/lisp/org-ctags.el
index 6431a2765..c6f7fc708 100644
--- a/lisp/org-ctags.el
+++ b/lisp/org-ctags.el
@@ -161,6 +161,20 @@ (defcustom org-ctags-path-to-ctags
   :version "24.1"
   :type 'file)
 
+(defconst org-ctags--open-link-functions-list
+  (list
+   #'org-ctags-find-tag
+   #'org-ctags-ask-rebuild-tags-file-then-find-tag
+   #'org-ctags-rebuild-tags-file-then-find-tag
+   #'org-ctags-ask-append-topic
+   #'org-ctags-append-topic
+   #'org-ctags-ask-visit-buffer-or-file
+   #'org-ctags-visit-buffer-or-file
+   #'org-ctags-fail-silently)
+  "Options for `org-open-link-functions'.
+Ensure that the user option and `unload-feature'
+use the same set of functions.")
+
 (defcustom org-ctags-open-link-functions
   '(org-ctags-find-tag
     org-ctags-ask-rebuild-tags-file-then-find-tag
@@ -168,14 +182,7 @@ (defcustom org-ctags-open-link-functions
   "List of functions to be prepended to ORG-OPEN-LINK-FUNCTIONS by ORG-CTAGS."
   :version "24.1"
   :type 'hook
-  :options '(org-ctags-find-tag
-             org-ctags-ask-rebuild-tags-file-then-find-tag
-             org-ctags-rebuild-tags-file-then-find-tag
-             org-ctags-ask-append-topic
-             org-ctags-append-topic
-             org-ctags-ask-visit-buffer-or-file
-             org-ctags-visit-buffer-or-file
-             org-ctags-fail-silently))
+  :options org-ctags--open-link-functions-list)
 
 
 (defvar org-ctags-tag-list nil
@@ -191,18 +198,20 @@ (defcustom org-ctags-new-topic-template
   :type 'string)
 
 
-(add-hook 'org-mode-hook
-          (lambda ()
-            (when (and org-ctags-enabled-p
-                       (buffer-file-name))
-              ;; Make sure this file's directory is added to default
-              ;; directories in which to search for tags.
-              (let ((tags-filename
-                     (expand-file-name
-                      (concat (file-name-directory (buffer-file-name))
-                              "/TAGS"))))
-                (when (file-exists-p tags-filename)
-                  (visit-tags-table tags-filename))))))
+(defun org-ctags--visit-tags-table ()
+  "Load tags for current file.
+A function for `org-mode-hook."
+  (when (and org-ctags-enabled-p
+             (buffer-file-name))
+    ;; Make sure this file's directory is added to default
+    ;; directories in which to search for tags.
+    (let ((tags-filename
+           (expand-file-name
+            (concat (file-name-directory (buffer-file-name))
+                    "/TAGS"))))
+      (when (file-exists-p tags-filename)
+        (visit-tags-table tags-filename)))))
+(add-hook 'org-mode-hook #'org-ctags--visit-tags-table)
 
 
 (advice-add 'visit-tags-table :after #'org--ctags-load-tag-list)
@@ -219,6 +228,17 @@ (defun org-ctags-enable ()
     (add-hook 'org-open-link-functions fn t)))
 
 
+(defun org-ctags-unload-function ()
+  "Disable `org-ctags' library.
+Called by `unload-feature'."
+  (put 'org-mode 'find-tag-default-function nil)
+  (advice-remove 'visit-tags-table #'org--ctags-load-tag-list)
+  (advice-remove 'xref-find-definitions
+                 #'org--ctags-set-org-mark-before-finding-tag)
+  (dolist (fn org-ctags--open-link-functions-list)
+    (remove-hook 'org-open-link-functions fn nil)))
+
+
 ;;; General utility functions.  ===============================================
 ;; These work outside org-ctags mode.
 
-- 
2.39.2


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From 5915811995f83fbfb89606bfa4f316d2b4521268 Mon Sep 17 00:00:00 2001
From: Max Nikulin <manikulin@gmail.com>
Date: Mon, 29 Apr 2024 23:28:29 +0700
Subject: [PATCH 2/2] org-ctags.el: Do not activate on load

* etc/ORG-NEWS: Announce the change breaking for `org-ctags' users and
provide init file code to enable the feature.
* lisp/org-ctags.el (org-ctags-enable): Do no invoke this function
during library loading.  Collect all initialization code in its body.

Setting up hooks during library loading leads to various issues.
- Emacs coding conventions insist on incompatible changes if loading
  a library modifies behavior, see
  Info node `(elisp) Coding Conventions'.
- The library may be autoloaded for the sake of help completion
  breaking `org-open-at-point':
  Nick Dokos. org-ctags land grab. Mon, 20 Mar 2023 23:36:09 -0400.
  <https://list.orgmode.org/87o7omg4ie.fsf@alphaville.usersys.redhat.com>
- Unrelated unit tests fail due to user prompt:
  Ihor Radchenko. Re: [PATCH] org-ctags.el: Protect shell specials
  in directory name. Sun, 28 Apr 2024 12:53:38 +0000.
  <https://list.orgmode.org/87a5ldk5rh.fsf@localhost>
---
 etc/ORG-NEWS      | 12 ++++++++++++
 lisp/org-ctags.el | 17 +++++++++++------
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/etc/ORG-NEWS b/etc/ORG-NEWS
index 06d3cf093..fea38e54e 100644
--- a/etc/ORG-NEWS
+++ b/etc/ORG-NEWS
@@ -641,6 +641,18 @@ This behaviour has been expanded to store an additional =CUSTOM_ID=
 link when storing any type of external link type in an Org file, not
 just =id:= links.
 
+*** ~org-ctags~ is not activated by default any more
+
+To follow Emacs [[info:elisp#Coding Conventions][coding conventions]] and to avoid confusion of users
+who accidentally get ~org-ctags~ autoloaded due to help completion,
+the library does not modify ~org-open-link-functions~ during loading
+any more.  Run ~org-ctags-enable~ to setup hooks and advices:
+
+#+begin_src emacs-lisp
+(with-eval-after-load "org-ctags"
+  (org-ctags-enable))
+#+end_src
+
 ** New and changed options
 *** ~org-babel-lua-multiple-values-separator~
 
diff --git a/lisp/org-ctags.el b/lisp/org-ctags.el
index c6f7fc708..784147572 100644
--- a/lisp/org-ctags.el
+++ b/lisp/org-ctags.el
@@ -57,6 +57,12 @@ ;;; Commentary:
 ;;    (add-hook 'org-mode-hook
 ;;      (lambda ()
 ;;        (define-key org-mode-map "\C-co" 'org-ctags-find-tag-interactive)))
+;;    (with-eval-after-load "org-ctags"
+;;      (org-ctags-enable))
+;;
+;; To activate the library, you need to call `org-ctags-enable' explicitly.
+;; It used to be invoked during library loading, but it was against Emacs
+;; policy and caused inconvenience of Org users who do not use `org-ctags'.
 ;;
 ;; By default, with org-ctags loaded, org will first try and visit the tag
 ;; with the same name as the link; then, if unsuccessful, ask the user if
@@ -211,10 +217,8 @@ (defun org-ctags--visit-tags-table ()
                     "/TAGS"))))
       (when (file-exists-p tags-filename)
         (visit-tags-table tags-filename)))))
-(add-hook 'org-mode-hook #'org-ctags--visit-tags-table)
 
 
-(advice-add 'visit-tags-table :after #'org--ctags-load-tag-list)
 (defun org--ctags-load-tag-list (&rest _)
   (when (and org-ctags-enabled-p tags-file-name)
     (setq-local org-ctags-tag-list
@@ -222,6 +226,11 @@ (defun org--ctags-load-tag-list (&rest _)
 
 
 (defun org-ctags-enable ()
+  (add-hook 'org-mode-hook #'org-ctags--visit-tags-table)
+  (advice-add 'visit-tags-table :after #'org--ctags-load-tag-list)
+  (advice-add 'xref-find-definitions :before
+              #'org--ctags-set-org-mark-before-finding-tag)
+
   (put 'org-mode 'find-tag-default-function 'org-ctags-find-tag-at-point)
   (setq org-ctags-enabled-p t)
   (dolist (fn org-ctags-open-link-functions)
@@ -314,8 +323,6 @@ (defun org-ctags-open-file (name &optional title)
 ;;;; Misc interoperability with etags system =================================
 
 
-(advice-add 'xref-find-definitions :before
-            #'org--ctags-set-org-mark-before-finding-tag)
 (defun org--ctags-set-org-mark-before-finding-tag (&rest _)
   "Before trying to find a tag, save our current position on org mark ring."
   (save-excursion
@@ -543,8 +550,6 @@ (defun org-ctags-find-tag-interactive ()
 	 'org-open-link-functions tag))))))
 
 
-(org-ctags-enable)
-
 (provide 'org-ctags)
 
 ;;; org-ctags.el ends here
-- 
2.39.2