Reimplement execute-extended-command in Elisp.

* src/keyboard.c (Fexecute_extended_command, Vsuggest_key_bindings):
Move to simple.el.
* lisp/simple.el (suggest-key-bindings, execute-extended-command):
Move from keyboard.c.

2 files changed, 62 insertions, 6 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index cb7e1377c92..cfc40bc01a8 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,10 +1,16 @@
+2012-05-01  Aaron S. Hawley  <aaron.s.hawley@gmail.com>
+            Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * simple.el (suggest-key-bindings, execute-extended-command):
+        Move from keyboard.c.
+
 2012-05-01  Chong Yidong  <cyd@gnu.org>
 
         * follow.el: Eliminate advice.
         (set-process-filter, process-filter, sit-for): Advice deleted.
         (follow-mode-off-hook): Obsolete hook removed.
-        (follow-avoid-tail-recenter-p, follow-process-filter-alist): Vars
-        deleted.
+        (follow-avoid-tail-recenter-p, follow-process-filter-alist):
+        Vars deleted.
         (follow-auto): Use a :set function.
         (follow-mode): Rewritten.  Don't advise process filters.
         (follow-switch-to-current-buffer-all, follow-scroll-up)
@@ -25,13 +31,13 @@
         (follow-stop-intercept-process-output, follow-generic-filter):
         Functions deleted.
         (follow-scroll-bar-toolkit-scroll, follow-scroll-bar-drag)
-        (follow-scroll-bar-scroll-up, follow-scroll-bar-scroll-down): New
-        functions, replacing advice on scroll-bar-* commands.
+        (follow-scroll-bar-scroll-up, follow-scroll-bar-scroll-down):
+        New functions, replacing advice on scroll-bar-* commands.
         (follow-mwheel-scroll): New function (Bug#4112).
 
         * comint.el (comint-adjust-point): New function.
-        (comint-postoutput-scroll-to-bottom): Use it.  Call
-        follow-comint-scroll-to-bottom for Follow mode buffers.
+        (comint-postoutput-scroll-to-bottom): Use it.
+        Call follow-comint-scroll-to-bottom for Follow mode buffers.
 
 2012-05-01  Glenn Morris  <rgm@gnu.org>
 
diff --git a/lisp/simple.el b/lisp/simple.el
index 55f7d1261ee..3d8a3a38dbd 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -1354,6 +1354,56 @@ to get different commands to edit and resubmit."
              "M-x ")
      obarray 'commandp t nil 'extended-command-history)))
 
+(defcustom suggest-key-bindings t
+  "Non-nil means show the equivalent key-binding when M-x command has one.
+The value can be a length of time to show the message for.
+If the value is non-nil and not a number, we wait 2 seconds."
+  :group 'keyboard
+  :type '(choice (const :tag "off" nil)
+                 (integer :tag "time" 2)
+                 (other :tag "on")))
+
+(defun execute-extended-command (prefixarg &optional command-name)
+  ;; Based on Fexecute_extended_command in keyboard.c of Emacs.
+  ;; Aaron S. Hawley <aaron.s.hawley(at)gmail.com> 2009-08-24
+  "Read function name, then read its arguments and call it.
+
+To pass a numeric argument to the command you are invoking with, specify
+the numeric argument to this command.
+
+Noninteractively, the argument PREFIXARG is the prefix argument to
+give to the command you invoke, if it asks for an argument."
+  (interactive (list current-prefix-arg (read-extended-command)))
+  ;; Emacs<24 calling-convention was with a single `prefixarg' argument.
+  (if (null command-name) (setq command-name (read-extended-command)))
+  (let* ((function (and (stringp command-name) (intern-soft command-name)))
+         (binding (and suggest-key-bindings
+                        (not executing-kbd-macro)
+                        (where-is-internal function overriding-local-map t))))
+    (unless (commandp function)
+      (error "`%s' is not a valid command name" command-name))
+    ;; Set this_command_keys to the concatenation of saved-keys and
+    ;; function, followed by a RET.
+    (setq this-command function)
+    (let ((prefix-arg prefixarg))
+      (command-execute function 'record))
+    ;; If enabled, show which key runs this command.
+    (when binding
+      ;; But first wait, and skip the message if there is input.
+      (let* ((waited
+              ;; If this command displayed something in the echo area;
+              ;; wait a few seconds, then display our suggestion message.
+              (sit-for (cond
+                        ((zerop (length (current-message))) 0)
+                        ((numberp suggest-key-bindings) suggest-key-bindings)
+                        (t 2)))))
+        (when (and waited (not (consp unread-command-events)))
+          (with-temp-message
+              (format "You can run the command `%s' with %s"
+                      function (key-description binding))
+            (sit-for (if (numberp suggest-key-bindings)
+                         suggest-key-bindings
+                       2))))))))
 
 (defvar minibuffer-history nil
   "Default minibuffer history list.