bug#46594: [External] : bug#46594: Use short answers

[Juri Linkov <juri@linkov.net>]

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>> > This is a related option, but I'm not sure if it should be mentioned
>> > in the docstring.  Maybe a simple reference should be sufficient?
>> 
>> I think mentioning it in the `yes-or-no-p' doc string would be good.
>
> I think that the doc for this option should explicitly discourage
> using the value that abbreviates, and say why.
>
> It should say that `yes-or-no-p' is _intended_ to be used when it's
> thought that you should not respond too quickly.  At least point that
> out, for users to think about before customizing.

Thanks for suggestions.  Now below is a new patch with these changes.

> Presumably this option is being added because there are apparently
> a lot of users who don't want to be slowed down by `yes-or-no-p'.
> But that's exactly the point of `yes-or-no-p'.

For many users using longer answers doesn't protect from mistakes.
Sometimes I execute a command without verifying if it's right,
e.g. first running a harmless command, then a more dangerous,
then I forget about the last command, and thinking that the last one
was the harmless command, quickly type a key sequence 'M-! M-p RET'.


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diff --git a/etc/NEWS b/etc/NEWS
index 2bad41f5ee..590fea5c97 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2408,6 +2408,11 @@ and display the result.
 When non-nil, then functions 'read-char-choice' and 'y-or-n-p' (respectively)
 use the function 'read-key' to read a character instead of using the minibuffer.
 
+---
+** New variable 'use-short-answers' to use 'y-or-n-p' instead of 'yes-or-no-p'.
+This relieves of the need to define an alias that maps one to another
+in the init file.
+
 +++
 ** 'set-window-configuration' now takes an optional 'dont-set-frame'
 parameter which, when non-nil, instructs the function not to select
diff --git a/lisp/cus-start.el b/lisp/cus-start.el
index c0a4a6dda0..d17c419c36 100644
--- a/lisp/cus-start.el
+++ b/lisp/cus-start.el
@@ -302,6 +302,7 @@ minibuffer-prompt-properties--setter
 	     ;; fns.c
 	     (use-dialog-box menu boolean "21.1")
 	     (use-file-dialog menu boolean "22.1")
+	     (use-short-answers menu boolean "28.1")
 	     (focus-follows-mouse
               frames (choice
                       (const :tag "Off (nil)" :value nil)
diff --git a/lisp/emacs-lisp/map-ynp.el b/lisp/emacs-lisp/map-ynp.el
index 14112a1c14..86a0c76fd1 100644
--- a/lisp/emacs-lisp/map-ynp.el
+++ b/lisp/emacs-lisp/map-ynp.el
@@ -265,7 +265,8 @@ read-answer-short
   "If non-nil, `read-answer' accepts single-character answers.
 If t, accept short (single key-press) answers to the question.
 If nil, require long answers.  If `auto', accept short answers if
-the function cell of `yes-or-no-p' is set to `y-or-n-p'."
+`use-short-answers' is non-nil, or the function cell of `yes-or-no-p'
+is set to `y-or-n-p'."
   :type '(choice (const :tag "Accept short answers" t)
                  (const :tag "Require long answer" nil)
                  (const :tag "Guess preference" auto))
@@ -304,7 +305,8 @@ read-answer
 
 When `use-dialog-box' is t, pop up a dialog window to get user input."
   (let* ((short (if (eq read-answer-short 'auto)
-                    (eq (symbol-function 'yes-or-no-p) 'y-or-n-p)
+                    (or use-short-answers
+                        (eq (symbol-function 'yes-or-no-p) 'y-or-n-p))
                   read-answer-short))
          (answers-with-help
           (if (assoc "help" answers)
diff --git a/src/fns.c b/src/fns.c
index c16f9c6399..7ab4bb525d 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -2873,6 +2873,11 @@ DEFUN ("yes-or-no-p", Fyes_or_no_p, Syes_or_no_p, 1, 1, 0,
       return obj;
     }
 
+  if (use_short_answers)
+    {
+      return call1 (intern ("y-or-n-p"), prompt);
+    }
+
   AUTO_STRING (yes_or_no, "(yes or no) ");
   prompt = CALLN (Fconcat, prompt, yes_or_no);
 
@@ -5904,6 +5909,15 @@ syms_of_fns (void)
 this variable.  */);
   use_file_dialog = true;
 
+  DEFVAR_BOOL ("use-short-answers", use_short_answers,
+    doc: /* Non-nil means `yes-or-no-p' uses shorter answers "y" or "n".
+It's discouraged to use single-key answers because `yes-or-no-p' is
+intended to be used when it's thought that you should not respond too
+quickly, and giving the wrong answer would have serious consequences.
+When non-nil, it uses `y-or-n-p'.  In this case it means also obeying
+the value of `y-or-n-p-use-read-key'.  */);
+  use_short_answers = false;
+
   defsubr (&Sidentity);
   defsubr (&Srandom);
   defsubr (&Slength);