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The editor command loop sets several Lisp variables to keep status
records for itself and for commands that are run. With the exception of
this-command and last-command it’s generally a bad idea to
change any of these variables in a Lisp program.
This variable records the name of the previous command executed by the command loop (the one before the current command). Normally the value is a symbol with a function definition, but this is not guaranteed.
The value is copied from this-command when a command returns to
the command loop, except when the command has specified a prefix
argument for the following command.
This variable is always local to the current terminal and cannot be buffer-local. See Multiple Terminals.
This variable is set up by Emacs just like last-command,
but never altered by Lisp programs.
This variable stores the most recently executed command that was not
part of an input event. This is the command repeat will try to
repeat, See Repeating in The GNU Emacs Manual.
This variable records the name of the command now being executed by
the editor command loop. Like last-command, it is normally a symbol
with a function definition.
The command loop sets this variable just before running a command, and
copies its value into last-command when the command finishes
(unless the command specified a prefix argument for the following
command).
Some commands set this variable during their execution, as a flag for
whatever command runs next. In particular, the functions for killing text
set this-command to kill-region so that any kill commands
immediately following will know to append the killed text to the
previous kill.
If you do not want a particular command to be recognized as the previous
command in the case where it got an error, you must code that command to
prevent this. One way is to set this-command to t at the
beginning of the command, and set this-command back to its proper
value at the end, like this:
(defun foo (args…)
(interactive …)
(let ((old-this-command this-command))
(setq this-command t)
…do the work…
(setq this-command old-this-command)))
We do not bind this-command with let because that would
restore the old value in case of error—a feature of let which
in this case does precisely what we want to avoid.
This has the same value as this-command except when command
remapping occurs (see Remapping Commands). In that case,
this-command gives the command actually run (the result of
remapping), and this-original-command gives the command that
was specified to run but remapped into another command.
This function returns a string or vector containing the key sequence
that invoked the present command, plus any previous commands that
generated the prefix argument for this command. Any events read by the
command using read-event without a timeout get tacked on to the end.
However, if the command has called read-key-sequence, it
returns the last read key sequence. See Key Sequence Input. The
value is a string if all events in the sequence were characters that
fit in a string. See Input Events.
(this-command-keys)
;; Now use C-u C-x C-e to evaluate that.
⇒ "^U^X^E"
Like this-command-keys, except that it always returns the events
in a vector, so you don’t need to deal with the complexities of storing
input events in a string (see Strings of Events).
This function empties out the table of events for
this-command-keys to return. Unless keep-record is
non-nil, it also empties the records that the function
recent-keys (see Recording Input) will subsequently return.
This is useful after reading a password, to prevent the password from
echoing inadvertently as part of the next command in certain cases.
This variable holds the last input event read as part of a key sequence, not counting events resulting from mouse menus.
One use of this variable is for telling x-popup-menu where to pop
up a menu. It is also used internally by y-or-n-p
(see Yes-or-No Queries).
This variable is set to the last input event that was read by the
command loop as part of a command. The principal use of this variable
is in self-insert-command, which uses it to decide which
character to insert.
last-command-event
;; Now use C-u C-x C-e to evaluate that.
⇒ 5
The value is 5 because that is the ASCII code for C-e.
This variable records which frame the last input event was directed to. Usually this is the frame that was selected when the event was generated, but if that frame has redirected input focus to another frame, the value is the frame to which the event was redirected. See Input Focus.
If the last event came from a keyboard macro, the value is macro.
Next: Adjusting Point, Previous: Distinguish Interactive, Up: Command Loop [Contents][Index]