Add prelude-undo-tree custom variable (#1428)

CHANGELOG.md

@@ -24,6 +24,8 @@
 * Replace prelude-go backend with `lsp` instead of unmaintained tools.
 * Use `rust-analyzer` as language server for prelude-rust and provide nicer syntax highlighting with `tree-sitter`.
 * Use `js2-mode` for Node.js specific `.cjs` and `.mjs` extensions.
+* Add `prelude-undo-tree` custom variable: allows user disable
+  undo-tree integration. Enabled by default to maintain backward-compatibility.
 
 ### Bugs fixed
 

core/prelude-custom.el

@@ -66,6 +66,11 @@ or desktop environments that make heavy use of them."
   :type 'boolean
   :group 'prelude)
 
+(defcustom prelude-undo-tree t
+  "Non-nil values enable Prelude's undo-tree integration."
+  :type 'boolean
+  :group 'prelude)
+
 (defcustom prelude-clean-whitespace-on-save t
   "Cleanup whitespace from file before it's saved.
 Will only occur if `prelude-whitespace' is also enabled."

core/prelude-editor.el

@@ -358,14 +358,20 @@ indent yanked text (with prefix arg don't indent)."
 ;; enable Prelude's keybindings
 (prelude-mode t)
 
-;; supercharge your undo/redo with undo-tree
-(require 'undo-tree)
-;; autosave the undo-tree history
-(setq undo-tree-history-directory-alist
-      `((".*" . ,temporary-file-directory)))
-(setq undo-tree-auto-save-history t)
-(global-undo-tree-mode)
-(diminish 'undo-tree-mode)
+(defun prelude-maybe-enable-undo-tree ()
+  "Enable `undo-tree' if `prelude-undo-tree' is not nil."
+  (when prelude-undo-tree
+    ;; supercharge your undo/redo with undo-tree
+    (require 'undo-tree)
+    ;; autosave the undo-tree history
+    (setq undo-tree-history-directory-alist
+          `((".*" . ,temporary-file-directory)))
+    (setq undo-tree-auto-save-history t)
+    (global-undo-tree-mode)
+    (diminish 'undo-tree-mode)))
+
+
+(prelude-maybe-enable-undo-tree)
 
 ;; enable winner-mode to manage window configurations
 (winner-mode +1)