From 13b9268374669c368343ce4279041f2021b264f6 Mon Sep 17 00:00:00 2001
From: Lars Ingebrigtsen <larsi@gnus.org>
Date: Mon, 14 Feb 2022 11:20:41 +0100
Subject: [PATCH] Add a mechanism for querying before executing a command

* doc/emacs/custom.texi (Disabling): Document it.
* doc/lispref/commands.texi (Disabling Commands): Document the
low-level stuff.

* lisp/simple.el (command-execute): Respect the `(query ...)'
value for `disabled'.
(command-execute--query): New function.
(command-query): New function.
---
 doc/emacs/custom.texi     | 16 ++++++++++++++++
 doc/lispref/commands.texi |  9 +++++++++
 etc/NEWS                  |  5 +++++
 lisp/simple.el            | 28 ++++++++++++++++++++++++----
 4 files changed, 54 insertions(+), 4 deletions(-)

diff --git a/doc/emacs/custom.texi b/doc/emacs/custom.texi
index c4f112d6683..a3c9c7c206a 100644
--- a/doc/emacs/custom.texi
+++ b/doc/emacs/custom.texi
@@ -2234,6 +2234,22 @@ is included in the message displayed when the command is used:
      "It's better to use `kill-region' instead.\n")
 @end example
 
+@findex command-query
+  As a less heavy-handed alternative to disabling commands, you may
+want to be queried before executing a command.  For instance, to be
+queried before executing the @kbd{M->} (@code{end-of-buffer})
+command, you could put something like the following in your init file:
+
+@example
+(command-query
+ 'end-of-buffer
+ "Do you really want to go to the end of the buffer?")
+@end example
+
+By default, you'll be queried with a @kbd{y}/@kbd{n} question, but if
+you give a non-@code{nil} value to the third, optional argument,
+you'll be queried with @kbd{yes}/@kbd{no} instead.
+
 @findex disable-command
 @findex enable-command
   You can make a command disabled either by editing the initialization
diff --git a/doc/lispref/commands.texi b/doc/lispref/commands.texi
index 01aa1e1fa4b..a1628eabaa2 100644
--- a/doc/lispref/commands.texi
+++ b/doc/lispref/commands.texi
@@ -3945,6 +3945,15 @@ what happens when a disabled command is invoked interactively.
 Disabling a command has no effect on calling it as a function from Lisp
 programs.
 
+@findex command-query
+  The value of the @code{disabled} property can also be a list where
+the first element is the symbol @code{query}.  In that case, the user
+will be queried whether to execute the command.  The second element in
+the list should be @code{nil} or non-@code{nil} to say whether to use
+@code{y-or-n-p} or @code{yes-or-no-p}, respectively, and the third
+element is the question to use.  The @code{command-query} convenience
+function should be used to enable querying for a command.
+
 @deffn Command enable-command command
 Allow @var{command} (a symbol) to be executed without special
 confirmation from now on, and alter the user's init file (@pxref{Init
diff --git a/etc/NEWS b/etc/NEWS
index 0f956f18a20..cd8cec32d5d 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -152,6 +152,11 @@ An autoload definition appears just as a '(defun . NAME)' and the
 
 * Changes in Emacs 29.1
 
++++
+** New function 'command-query'.
+Commands that are marked with this function will prompt the user
+before executing.
+
 ---
 ** 'count-lines' will now report buffer totals if given a prefix.
 
diff --git a/lisp/simple.el b/lisp/simple.el
index 695871db505..accc119e2b3 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -2381,12 +2381,17 @@ don't clear it."
                        (setq current-prefix-arg prefix-arg)
                        (setq prefix-arg nil)
                        (when current-prefix-arg
-                         (prefix-command-update))))))
+                         (prefix-command-update)))))
+        query)
     (if (and (symbolp cmd)
              (get cmd 'disabled)
-             disabled-command-function)
-        ;; FIXME: Weird calling convention!
-        (run-hooks 'disabled-command-function)
+             (or (and (setq query (and (consp (get cmd 'disabled))
+                                       (eq (car (get cmd 'disabled)) 'query)))
+                      (not (command-execute--query cmd)))
+                 (and (not query) disabled-command-function)))
+        (when (not query)
+          ;; FIXME: Weird calling convention!
+          (run-hooks 'disabled-command-function))
       (let ((final cmd))
         (while
             (progn
@@ -2410,6 +2415,21 @@ don't clear it."
               (put cmd 'command-execute-obsolete-warned t)
               (message "%s" (macroexp--obsolete-warning
                              cmd (get cmd 'byte-obsolete-info) "command"))))))))))
+
+(defun command-execute--query (command)
+  "Query the user whether to run COMMAND."
+  (let ((query (get command 'disabled)))
+    (funcall (if (nth 1 query) #'yes-or-no-p #'y-or-n-p)
+             (nth 2 query))))
+
+;;;###autoload
+(defun command-query (command query &optional verbose)
+  "Make executing COMMAND issue QUERY to the user.
+This will, by default, use `y-or-n-p', but if VERBOSE,
+`yes-or-no-p' is used instead."
+  (put command 'disabled
+       (list 'query (not (not verbose)) query)))
+
 
 (defvar minibuffer-history nil
   "Default minibuffer history list.
-- 
2.39.5