How to automatically select an option in a specific prompt?

Question

When I'm programming Python, I will use rope to rename variables (using ropemacs). rope-rename pops up a dialogue after you provide a new variable name, where you can preview the change, cancel, or perform the refactoring.

For example:

Choose what to do: [perform]  {perform | preview | cancel}

"perform" is always the default option. 90% of the time, I don't want to go through this menu, I just want to to select the default option.

Is there any way to advise a command to automatically choose a specific (or the default) dialogue option so I can skip this menu? Is there maybe a package that allows me to specify automatic selections in dialogues matching certain conditions?

Answer 1

After delving into the innards of the minibuffer, I've developed a solution that should work for all prompting functions. It's pretty hacky though.

This method intercepts the prompt function itself (read-from-minibuffer) and returns the default value - iff the prompt matches one of a list of regular expressions. This could be extended to return a specific value (other than the default), based on the prompt.

This is the code:

;; First, we set up a global list of regular expressions. This
;; variable should only be modified by auto-pick-default-prompt. A
;; prompt that matches any of these regular expressions will be
;; accepted automatically.
(setq auto-pick-default-prompts '())


(defun auto-pick-default-internal (original-function
                                   prompt
                                   &optional initial-contents key-map
                                   read history default-value
                                   inherit-input-method)
  "Function to be run around prompts to auto-pick default value.

Uses the global variable auto-pick-default-prompts to
determine whether the particular prompt it is enclosing should be
automatically confirmed.

If no regular expressions for prompts are specified, auto
confirms all prompts."
  ;; If no prompt filters have been set, just return the default value
  ;; for the prompt
  (if (not auto-pick-default-prompts)
      default-value
    ;; Else check if the prompt matches one of the filters.
    ;; If so, return the default value for the prompt.
    (let ((matches nil))
      (mapc #'(lambda (regexp)
                (if (string-match regexp prompt)
                    (setq matches t)))
            auto-pick-default-prompts)
      (if matches
          default-value
        (funcall original-function
                 prompt initial-contents key-map read history
                 default-value inherit-input-method)))))


(defun auto-pick-default-prompt (function is-interactive prompt-regexps &optional args)
  "Runs a function, auto selecting the default option in prompts.

Takes a list of regular expressions for prompts that should be
auto-confirmed. Prompts which do not match any of these
expressions will not be auto confirmed."
  (condition-case nil
      (progn
        ;; Set the prompts that should be auto-accepted
        (setq auto-pick-default-prompts prompt-regexps)
        ;; Add the intercepting command
        (advice-add 'read-from-minibuffer :around #'auto-pick-default-internal)
        ;; Call the function in the appropriate manner (interactive,
        ;; with arguments, without arguments)
        (if is-interactive
            (if (> (length args) 0)
                (call-interactively function nil args)
              (call-interactively function))
          (apply function args))
        ;; Now remove the intercepting command and reset the prompts
        ;; that should be auto-accepted.
        (advice-remove 'read-from-minibuffer #'auto-pick-default-internal)
        (setq auto-pick-default-prompts nil))
    ((debug error) (progn
                     ;; This function wraps a child function with some
                     ;; advice. If the child throws an error, the
                     ;; advice will not be removed. Explicitly remove
                     ;; advice after an error has been thrown.
                     (advice-remove 'read-from-minibuffer #'auto-pick-default-internal)
                     (setq auto-pick-default-prompts nil)            
                     (signal err)))))


(defun noprompt-rope-rename (&rest args)
  "Call rope-rename, skipping the confirmation prompt."
  (interactive "P")
  (let ((prompts-to-skip'("Choose what to do")))
    (auto-pick-default-prompt 'rope-rename t prompts-to-skip)))

A limitation of this approach is that it can't be called recursively. A command wrapped by auto-pick-default-prompt cannot itself call auto-pick-default-prompt. That should be fine though, and I imagine it's possible to get around this limitation by extending the advice system.