Toggle fixes when purpose-mode is toggled (#180)

* Toggle fixes when purpose-mode is toggled

Toggle the integration fixes on when purpose-mode is activated, and toggle them
off when purpose-mode is deactivated. Mainly, this means the relevant advices
are now active only while purpose-mode is active.

window-purpose-fixes.el

@@ -29,6 +29,43 @@
 (require 'window-purpose-switch)
 (require 'window-purpose-configuration)
 
+(defvar purpose-fix-togglers-hook nil
+  "List of functions that toggle fixes.
+Each function in the list is responsible to toggle a fix. Each
+function should take no argument, and enable its fix if
+`purpose-mode' is non-nil, and disable it if `purpose-mode' is
+nil. Functions should be added to this variable via `add-hook'.")
+
+;; variable `purpose-mode' may not be defined yet, so declare it here (without a
+;; value) to satisfy the byte-compiler.
+(defvar purpose-mode)
+
+(defun purpose-toggle-advice (symbol where function)
+  "Add advice or remove advice, depending on the value of `purpose-mode'.
+If `purpose-mode' is active, then add FUNCTION to SYMBOL
+according to WHERE, otherwise remove FUNCTION from SYMBOL. Refer
+to `advice-add' and `advice-remove' for further details of
+SYMBOL, WHERE and FUNCTION."
+  (if purpose-mode
+      (advice-add symbol where function)
+    (advice-remove symbol function)))
+
+(defmacro purpose-advice-toggler (symbol where function)
+  "Return a function that adds or removes an advice, depending on
+  the value of `purpose-mode'."
+  ;; no need for memoization. It's ok to return a lambda, because even if called
+  ;; twice with same args, adding the two results to the same hook will not
+  ;; create duplications in the hook: `add-hook' is smart enough to consider two
+  ;; closures with equal code (and same captured values) as equal objects (it
+  ;; checks equality with `member', which compares with `equal'). Verified with
+  ;; Emacs 27.1
+  `(lambda ()
+     (purpose-toggle-advice ,symbol ,where ,function)))
+
+(defun purpose-install-advice-toggler (symbol where function)
+  (purpose-toggle-advice symbol where function)
+  (add-hook 'purpose-fix-togglers-hook (purpose-advice-toggler symbol where function)))
+
 (defun purpose--fix-edebug ()
   "Integrates Edebug with Purpose."
 
@@ -55,7 +92,9 @@ spliting logic with `pop-to-buffer'."
       (unless (memq (framep (selected-frame)) '(nil t pc))
         (x-focus-frame (selected-frame)))
       (set-window-hscroll window 0))
-    (advice-add 'edebug-pop-to-buffer :override 'purpose--edebug-pop-to-buffer-advice)))
+
+    (purpose-install-advice-toggler 'edebug-pop-to-buffer :override
+                                    'purpose--edebug-pop-to-buffer-advice)))
 
 ;;; `compilation-next-error-function' sometimes hides the compilation buffer
 ;;; when Purpose is on. Solution: make the buffer's window dedicated while
@@ -98,7 +137,8 @@ window-purpose."
     (interactive (lambda (spec) (advice-eval-interactive-spec spec)))
     (let ((display-buffer-overriding-action '(purpose--action-function . nil)))
       (apply oldfun args)))
-  (advice-add 'next-error :around 'purpose--next-error))
+
+  (purpose-install-advice-toggler 'next-error :around 'purpose--next-error))
 
 
 ;;; Hydra's *LV* buffer should be ignored by Purpose
@@ -187,10 +227,11 @@ When `purpose--active-p' is nil, call original `neo-global--create-window'."
                '(Neotree purpose-display-reuse-window-buffer
                          purpose-display-reuse-window-purpose
                          purpose--fix-display-neotree))
-  (advice-add 'neo-global--create-window
-              :around 'purpose-fix-neotree-create-window-advice)
-  (advice-add 'neo-open-file
-              :around 'purpose-fix-neotree-open-file-advice))
+
+  (purpose-install-advice-toggler 'neo-global--create-window :around
+                                  'purpose-fix-neotree-create-window-advice)
+  (purpose-install-advice-toggler 'neo-open-file :around
+                                  'purpose-fix-neotree-open-file-advice))
 
 (defun purpose--fix-neotree ()
   "Call `purpose--fix-neotree-1' after `neotree' is loaded."
@@ -213,10 +254,11 @@ Don't call this function before `org' is loaded."
   (defun purpose--fix-org-get-location (oldfun &rest args)
     "Make Purpose inactive during `org-get-location'."
     (without-purpose (apply oldfun args)))
-  (advice-add 'org-switch-to-buffer-other-window
-              :around 'purpose--fix-org-switch-to-buffer-other-window)
-  (advice-add 'org-get-location
-              :around 'purpose--fix-org-get-location))
+
+  (purpose-install-advice-toggler 'org-switch-to-buffer-other-window :around
+                                  'purpose--fix-org-switch-to-buffer-other-window)
+  (purpose-install-advice-toggler 'org-get-location :around
+                                  'purpose--fix-org-get-location))
 
 (defun purpose--fix-org-no-popups ()
   "Call `purpose--fix-org-no-popups-1' after `org' is loaded."
@@ -233,8 +275,9 @@ Don't call this function before `popwin' is loaded."
   (defun purpose--fix-popwin-replicate (oldfun &rest args)
     "Make Purpose inactive during `popwin:replicate-window-config'."
     (without-purpose (apply oldfun args)))
-  (advice-add 'popwin:replicate-window-config
-              :around 'purpose--fix-popwin-replicate))
+
+  (purpose-install-advice-toggler 'popwin:replicate-window-config
+                                  :around 'purpose--fix-popwin-replicate))
 
 (defun purpose--fix-popwin ()
   "Call `purpose--fix-popwin-1' after `popwin' is loaded."
@@ -280,10 +323,11 @@ Don't call this function before `popwin' is loaded."
     (defun purpose--fix-magit-popup-help (oldfun &rest args)
       "Make Purpose inactive during `magit-popup-manpage'."
       (without-purpose (apply oldfun args)))
-    (advice-add 'magit-popup-describe-function
-                :around 'purpose--fix-magit-popup-help)
-    (advice-add 'magit-popup-manpage
-                :around 'purpose--fix-magit-popup-help)))
+
+    (purpose-install-advice-toggler 'magit-popup-describe-function
+                                    :around 'purpose--fix-magit-popup-help)
+    (purpose-install-advice-toggler 'magit-popup-manpage
+                                    :around 'purpose--fix-magit-popup-help)))
 
 
 
@@ -307,8 +351,9 @@ Don't call this function before `popwin' is loaded."
         (special-mode)
         (goto-char (point-min)))
       (switch-to-buffer buffer))
-    (advice-add 'whitespace-display-window :override
-                'purpose--whitespace-display-window-advice)))
+
+    (purpose-install-advice-toggler 'whitespace-display-window :override
+                                    'purpose--whitespace-display-window-advice)))
 
 
 ;;; install fixes
@@ -334,8 +379,8 @@ are:
   (unless (member 'edebug exclude)
     (purpose--fix-edebug))
   (unless (member 'compilation-next-error-function exclude)
-    (advice-add 'compilation-next-error-function
-                :around #'purpose--fix-compilation-next-error))
+    (purpose-install-advice-toggler 'compilation-next-error-function
+                                    :around #'purpose--fix-compilation-next-error))
   (unless (member 'isearch exclude)
     (purpose--fix-isearch))
   (unless (member 'next-error exclude)

window-purpose.el

@@ -298,9 +298,13 @@ This function is called when `purpose-mode' is deactivated."
         (setq display-buffer-overriding-action
               '(purpose--action-function . nil))
         (setq purpose--active-p t)
-        (purpose-fix-install))
+        (unless purpose-fix-togglers-hook
+          (purpose-fix-install))
+        (run-hooks 'purpose-fix-togglers-hook))
+
     (purpose--remove-advices)
-    (setq purpose--active-p nil)))
+    (setq purpose--active-p nil)
+    (run-hooks 'purpose-fix-togglers-hook)))
 
 (push '(purpose-dedicated . writable) window-persistent-parameters)
 (provide 'window-purpose)