bug#28525: 26.0.60; dired-delete-file: Accept y/n if yes-or-no-p is aliased to y-or-n-p

[Tino Calancha <tino.calancha@gmail.com>]

Tino Calancha <tino.calancha@gmail.com> writes:

> In my previous patch i checked if `yes-or-no-p' is aliased to
> `y-or-n-p'.
> A more general way is to add new functions `yes-or-no-or-else-p',
> `y-or-n-or-else-p': they ask the question and
> accept additional answers according with an optional argument.
Indeed, we don't need new functions just add an optional argument makes
the thing (see below patch).
In some cases it might be useful to allow more answers than just 'yes'
or 'no'.

(yes-or-no-p "Do it? ") ; Accepts 'yes' or 'no'

(yes-or-no-p "Do it? " '((l . later) (m . maybe)))
;; Also accepts 'later' and 'maybe'.

(y-or-n-p "Do it? " '((l . later) (m . maybe)))
;; Accepts: 'y', 'n', 'l' and 'm'.

This has the advantage that is backward compatible for users doing:
(fset 'yes-or-no-p 'y-or-n-p)

Then, these users can use the new feature answering '!', if
we write something like:
(yes-or-no-p "Recursively delete dir? " '((! . all) (q . quit) (h . help)))

--8<-----------------------------cut here---------------start------------->8---
commit 17b1d3715b3d07c487b5b9cc757fc2ce5e0a89a9
Author: Tino Calancha <tino.calancha@gmail.com>
Date:   Sun Oct 1 12:44:41 2017 +0900

    Accept more answers in yes-or-no-or-else-p and y-or-n-or-else-p
    
    * src/fns.c (yes-or-no-p)
    * lisp/subr.el (y-or-n-or-p):
    Add optional argument OTHERS.

diff --git a/lisp/subr.el b/lisp/subr.el
index cf15ec287f..1b11e84dd0 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -2484,8 +2484,13 @@ sit-for
 ;; Behind display-popup-menus-p test.
 (declare-function x-popup-dialog "menu.c" (position contents &optional header))
 
-(defun y-or-n-p (prompt)
-  "Ask user a \"y or n\" question.
+(defun y-or-n-p (prompt &optional others)
+  "Ask user a \"y or n r ...\" question.
+
+OTHERS is a list (INPUT . ACTION), with INPUT the user
+input, and ACTION determines how to proceed; both are symbols.
+For instance, SYMBOL might be '!' and ACTION 'automatic'.
+
 Return t if answer is \"y\" and nil if it is \"n\".
 PROMPT is the string to display to ask the question.  It should
 end in a space; `y-or-n-p' adds \"(y or n) \" to it.
@@ -2509,48 +2514,58 @@ y-or-n-p
   ;; ¡Beware! when I tried to edebug this code, Emacs got into a weird state
   ;; where all the keys were unbound (i.e. it somehow got triggered
   ;; within read-key, apparently).  I had to kill it.
-  (let ((answer 'recenter)
-	(padded (lambda (prompt &optional dialog)
-		  (let ((l (length prompt)))
-		    (concat prompt
-			    (if (or (zerop l) (eq ?\s (aref prompt (1- l))))
-				"" " ")
-			    (if dialog "" "(y or n) "))))))
+  (let* ((answer 'recenter)
+         (options (mapcar #'car others))
+         (options-str (mapconcat #'identity
+                                 (append (list "y" "n")
+                                         (mapcar (lambda (x) (symbol-name (car x))) others)) " or "))
+         (actions (append '(skip act) (mapcar #'cdr others)))
+	 (padded (lambda (prompt &optional dialog)
+		   (let ((l (length prompt)))
+		     (concat prompt
+			     (if (or (zerop l) (eq ?\s (aref prompt (1- l))))
+				 "" " ")
+			     (if dialog "" (concat "(" options-str ")")))))))
     (cond
      (noninteractive
       (setq prompt (funcall padded prompt))
       (let ((temp-prompt prompt))
-	(while (not (memq answer '(act skip)))
+	(while (not (memq answer actions))
 	  (let ((str (read-string temp-prompt)))
 	    (cond ((member str '("y" "Y")) (setq answer 'act))
+                  ((assoc (intern str) others) (setq answer (cdr (assoc (intern str) others))))
 		  ((member str '("n" "N")) (setq answer 'skip))
-		  (t (setq temp-prompt (concat "Please answer y or n.  "
+		  (t (setq temp-prompt (concat "Please answer " options-str ". "
 					       prompt))))))))
      ((and (display-popup-menus-p)
            last-input-event             ; not during startup
 	   (listp last-nonmenu-event)
 	   use-dialog-box)
       (setq prompt (funcall padded prompt t)
-	    answer (x-popup-dialog t `(,prompt ("Yes" . act) ("No" . skip)))))
+	    answer
+            (x-popup-dialog
+             t
+             `(,prompt ("Yes" . act) ("No" . skip)
+                       (mapcar (lambda (x) (cons (symbol-name (car x)) (cdr x))) others)))))
      (t
       (setq prompt (funcall padded prompt))
       (while
           (let* ((scroll-actions '(recenter scroll-up scroll-down
-				   scroll-other-window scroll-other-window-down))
+				            scroll-other-window scroll-other-window-down))
 		 (key
                   (let ((cursor-in-echo-area t))
                     (when minibuffer-auto-raise
                       (raise-frame (window-frame (minibuffer-window))))
                     (read-key (propertize (if (memq answer scroll-actions)
                                               prompt
-                                            (concat "Please answer y or n.  "
-                                                    prompt))
+                                            (concat "Please answer " options-str ". " prompt))
                                           'face 'minibuffer-prompt)))))
             (setq answer (lookup-key query-replace-map (vector key) t))
             (cond
-	     ((memq answer '(skip act)) nil)
-	     ((eq answer 'recenter)
-	      (recenter) t)
+	     ((memq answer actions) nil)
+	     ((member (intern (char-to-string key)) options)
+              (setq answer (cdr (assoc (intern (char-to-string key)) others))) nil)
+	     ((eq answer 'recenter) (recenter) t)
 	     ((eq answer 'scroll-up)
 	      (ignore-errors (scroll-up-command)) t)
 	     ((eq answer 'scroll-down)
@@ -2564,9 +2579,14 @@ y-or-n-p
 	     (t t)))
         (ding)
         (discard-input))))
-    (let ((ret (eq answer 'act)))
+    (let ((ret (cond ((eq answer 'act))
+                     ((eq answer 'skip) nil)
+                     ((memq answer actions) answer))))
       (unless noninteractive
-        (message "%s%c" prompt (if ret ?y ?n)))
+        (message "%s%c" prompt (cond ((eq ret t) ?y)
+                                     ((null ret) ?n)
+                                     ((memq ret actions)
+                                      (string-to-char (symbol-name (car (rassoc ret others))))))))
       ret)))
 
 \f
diff --git a/src/fns.c b/src/fns.c
index 4524ff9b26..a9e1a864cd 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -2582,20 +2582,27 @@ do_yes_or_no_p (Lisp_Object prompt)
   return call1 (intern ("yes-or-no-p"), prompt);
 }
 
-DEFUN ("yes-or-no-p", Fyes_or_no_p, Syes_or_no_p, 1, 1, 0,
-       doc: /* Ask user a yes-or-no question.
-Return t if answer is yes, and nil if the answer is no.
+DEFUN ("yes-or-no-p", Fyes_or_no_p, Syes_or_no_p, 1, 2, 0,
+       doc: /* Ask user a yes or no or ... question.
+OTHERS is a list (INPUT . ACTION), with INPUT the user
+input, and ACTION determines how to proceed; both are symbols.
+For instance, SYMBOL might be '!' and ACTION 'automatic'.
+
+Return t if answer is yes, nil if the answer is no or ACTION if the answer
+is ACTION.
 PROMPT is the string to display to ask the question.  It should end in
-a space; `yes-or-no-p' adds \"(yes or no) \" to it.
+a space; `yes-or-no-or-else-p' adds \"(yes or no or ACTION1 or ACTION2 ...) \" to it.
 
 The user must confirm the answer with RET, and can edit it until it
 has been confirmed.
 
 If dialog boxes are supported, a dialog box will be used
-if `last-nonmenu-event' is nil, and `use-dialog-box' is non-nil.  */)
-  (Lisp_Object prompt)
+if `last-nonmenu-event' is nil, and `use-dialog-box' is non-nil.
+
+This function is like `yes-or-no-p' with the additional answers in OTHERS.  */)
+  (Lisp_Object prompt, Lisp_Object others)
 {
-  Lisp_Object ans;
+  Lisp_Object ans, yes_or_no, actions, str;
 
   CHECK_STRING (prompt);
 
@@ -2611,9 +2618,21 @@ if `last-nonmenu-event' is nil, and `use-dialog-box' is non-nil.  */)
       return obj;
     }
 
-  AUTO_STRING (yes_or_no, "(yes or no) ");
-  prompt = CALLN (Fconcat, prompt, yes_or_no);
-
+  if (!NILP (others)) {
+    actions = Fmapcar (intern ("symbol-name"), Fmapcar (Qcdr, others));
+    yes_or_no = Fmapconcat (Qidentity,
+                            CALLN (Fappend, list2 (build_string ("yes"),
+                                                   build_string ("no")),
+                                   actions),
+                            build_string (" or "));
+    yes_or_no = CALLN (Fconcat, build_string ("("), yes_or_no, build_string (")"));
+  }
+  else {
+        actions = Qnil;
+        yes_or_no = build_string ("(yes or no)");
+  }
+  prompt = CALLN (Fconcat, prompt, yes_or_no, build_string (" "));
+  str = CALLN (Fconcat, build_string ("Please answer "), yes_or_no, build_string ("."));
   while (1)
     {
       ans = Fdowncase (Fread_from_minibuffer (prompt, Qnil, Qnil, Qnil,
@@ -2623,13 +2642,16 @@ if `last-nonmenu-event' is nil, and `use-dialog-box' is non-nil.  */)
 	return Qt;
       if (SCHARS (ans) == 2 && !strcmp (SSDATA (ans), "no"))
 	return Qnil;
+      if (!NILP (Fmember (ans, actions)))
+        return Fcdr (Frassoc (intern (SSDATA (ans)), others));
 
       Fding (Qnil);
       Fdiscard_input ();
-      message1 ("Please answer yes or no.");
+      message1 (SSDATA (str));
       Fsleep_for (make_number (2), Qnil);
     }
 }
+
 \f
 DEFUN ("load-average", Fload_average, Sload_average, 0, 1, 0,
        doc: /* Return list of 1 minute, 5 minute and 15 minute load averages.

--8<-----------------------------cut here---------------end--------------->8---
 In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.11)
 of 2017-09-30
 Repository revision: 20a09de953f437109a098fa8c4d380663d921481