Clarify what constitutes an event (bug#35238)

* doc/lispref/commands.texi (Input Events): Specify that events are
non-nil and remove vestiges of bug#10190.
* doc/lispref/os.texi (Recording Input): Document optional argument
of recent-keys.
* lisp/subr.el (eventp): Check that the car of conses is non-nil.
* etc/NEWS: Announce it as an incompatible change.
* src/keyboard.c (Frecent_keys): Clarify that returned "events" are
not real events.

diff --git a/doc/lispref/commands.texi b/doc/lispref/commands.texi
index cd44c1c87ef0f96c14785da622ecec8e489e5241..5ea0be2667b142d33b058d0266ad4eef7608e029 100644 (file)
--- a/doc/lispref/commands.texi
+++ b/doc/lispref/commands.texi
@@ -1047,12 +1047,9 @@ and meaning of input events in detail.
 This function returns non-@code{nil} if @var{object} is an input event
 or event type.
 
-Note that any symbol might be used as an event or an event type.
-@code{eventp} cannot distinguish whether a symbol is intended by Lisp
-code to be used as an event.  Instead, it distinguishes whether the
-symbol has actually been used in an event that has been read as input in
-the current Emacs session.  If a symbol has not yet been so used,
-@code{eventp} returns @code{nil}.
+Note that any non-@code{nil} symbol might be used as an event or an
+event type; @code{eventp} cannot distinguish whether a symbol is
+intended by Lisp code to be used as an event.
 @end defun
 
 @menu

diff --git a/doc/lispref/os.texi b/doc/lispref/os.texi
index 59cd5a8fe8aa2b5feb4b7fc77d57493a69d19d44..fef954eb7a3687e02ef485b9b73531564fe0a9df 100644 (file)
--- a/doc/lispref/os.texi
+++ b/doc/lispref/os.texi
@@ -2197,7 +2197,7 @@ is the character Emacs currently uses for quitting, usually @kbd{C-g}.
 @subsection Recording Input
 @cindex recording input
 
-@defun recent-keys
+@defun recent-keys &optional include-cmds
 This function returns a vector containing the last 300 input events from
 the keyboard or mouse.  All input events are included, whether or not
 they were used as parts of key sequences.  Thus, you always get the last
@@ -2205,6 +2205,11 @@ they were used as parts of key sequences.  Thus, you always get the last
 (These are excluded because they are less interesting for debugging; it
 should be enough to see the events that invoked the macros.)
 
+If @var{include-cmds} is non-@code{nil}, complete key sequences in the
+result vector are interleaved with pseudo-events of the form
+@code{(nil . @var{COMMAND})}, where @var{COMMAND} is the binding of
+the key sequence (@pxref{Command Overview}).
+
 A call to @code{clear-this-command-keys} (@pxref{Command Loop Info})
 causes this function to return an empty vector immediately afterward.
 @end defun

diff --git a/etc/NEWS b/etc/NEWS
index 5fe2e63526d55f3a0352c889a4feb7e40613d93f..72f669a4a408701e35f7eabf9ca6580121a8ab86 100644 (file)
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1575,6 +1575,11 @@ performs '(setq-local indent-line-function #'indent-relative)'.
 ** 'make-process' no longer accepts a non-nil ':stop' key.  This has
 never worked reliably, and now causes an error.
 
++++
+** 'eventp' no longer returns non-nil for lists whose car is nil.
+This is consistent with the fact that nil, though a symbol, is not a
+valid event type.
+
 \f
 * Lisp Changes in Emacs 27.1
 

diff --git a/lisp/subr.el b/lisp/subr.el
index f68f9dd4191acc11147f8a491431cba6cc5bc0e3..be21dc67a0d4ef7907d918d90091fdcccbe33263 100644 (file)
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -1238,12 +1238,14 @@ The normal global definition of the character C-x indirects to this keymap.")
                          c)))
            key)))
 
-(defun eventp (obj)
-  "True if the argument is an event object."
-  (when obj
-    (or (integerp obj)
-        (and (symbolp obj) obj (not (keywordp obj)))
-        (and (consp obj) (symbolp (car obj))))))
+(defun eventp (object)
+  "Return non-nil if OBJECT is an input event or event object."
+  (or (integerp object)
+      (and (if (consp object)
+               (setq object (car object))
+             object)
+           (symbolp object)
+           (not (keywordp object)))))
 
 (defun event-modifiers (event)
   "Return a list of symbols representing the modifier keys in event EVENT.

diff --git a/src/keyboard.c b/src/keyboard.c
index ea13c7f5bcdd251ad9a9db601701ab04eed8868b..5f2b7afe6d1ed566190c9cb5dd7fbce712a590bb 100644 (file)
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -9968,7 +9968,7 @@ If CHECK-TIMERS is non-nil, timers that are ready to run will do so.  */)
 DEFUN ("recent-keys", Frecent_keys, Srecent_keys, 0, 1, 0,
        doc: /* Return vector of last few events, not counting those from keyboard macros.
 If INCLUDE-CMDS is non-nil, include the commands that were run,
-represented as events of the form (nil . COMMAND).  */)
+represented as pseudo-events of the form (nil . COMMAND).  */)
   (Lisp_Object include_cmds)
 {
   bool cmds = !NILP (include_cmds);