New variable 'use-short-answers' to use 'y-or-n-p' instead of 'yes-or-no-p'

* lisp/cus-start.el: Add use-short-answers.

* lisp/emacs-lisp/map-ynp.el (read-answer): Handle use-short-answers.
(read-answer-short): Add use-short-answers to docstring.

* src/fns.c (Fyes_or_no_p): Call y-or-n-p if use_short_answers is true.
(syms_of_fns): Add DEFVAR_BOOL use-short-answers (bug#46594).

1 files changed, 14 insertions, 0 deletions

diff --git a/src/fns.c b/src/fns.c
index c16f9c63998..79b5a1e9930 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -2873,6 +2873,11 @@ if `last-nonmenu-event' is nil, and `use-dialog-box' is non-nil.  */)
       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 @@ that disables the use of a file dialog, regardless of the value of
 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, so you take time and perhaps think more about the answer.
+When non-nil, then `yes-or-no-p' uses `y-or-n-p' to read an answer.
+The same variable also affects the function `read-answer'.  */);
+  use_short_answers = false;
+
   defsubr (&Sidentity);
   defsubr (&Srandom);
   defsubr (&Slength);