Use setopt for "set" button if available

helpful.el

@@ -98,6 +98,12 @@ To disable cleanup entirely, set this variable to nil. See also
  :type 'function
  :group 'helpful)
 
+(defcustom helpful-set-variable-function
+ (if (< 29 emacs-major-version) #'setopt #'setq)
+ "Function used by `helpful--set' to interactively set variables."
+ :type 'function
+ :group 'helpful)
+
 ;; TODO: explore whether more basic highlighting is fast enough to
 ;; handle larger functions. See `c-font-lock-init' and its use of
 ;; font-lock-keywords-1.
@@ -600,6 +606,7 @@ overrides that to include previously opened buffers."
  (let* ((sym (button-get button 'symbol))
  (buf (button-get button 'buffer))
  (sym-value (helpful--sym-value sym buf))
+ (set-func (symbol-name helpful-set-variable-function))
  ;; Inspired by `counsel-read-setq-expression'.
  (expr
  (minibuffer-with-setup-hook
@@ -608,17 +615,17 @@ overrides that to include previously opened buffers."
  #'elisp-eldoc-documentation-function)
  (run-hooks 'eval-expression-minibuffer-setup-hook)
  (goto-char (minibuffer-prompt-end))
- (forward-char (length (format "(setq %S " sym))))
+ (forward-char (length (format "(%s %S " set-func sym))))
  (read-from-minibuffer
  "Eval: "
  (format
  (if (or (consp sym-value)
  (and (symbolp sym-value)
  (not (null sym-value))
  (not (keywordp sym-value))))
- "(setq %s '%S)"
- "(setq %s %S)")
- sym sym-value)
+ "(%s %s '%S)"
+ "(%s %s %S)")
+ set-func sym sym-value)
  read-expression-map t
  'read-expression-history))))
  (save-current-buffer