Commit f68903b3 authored by Kim F. Storm's avatar Kim F. Storm
Browse files

(Misc Events): User signals now result in sigusr1

and sigusr2 events which are handled through special-event-map.
(Special Events): User signals and drag-n-drop are special.
parent 6a7d16fe
......@@ -1586,14 +1586,33 @@ The precise meaning of the event parameters and the way these
parameters are used to display the help-echo text are described in
@ref{Text help-echo}.
@cindex @code{signal usr1} event
@cindex @code{signal usr2} event
@cindex @code{sigusr1} event
@cindex @code{sigusr2} event
@cindex user signals
@item signal usr1
@itemx signal usr2
These event sequences are generated when the Emacs process receives
@item sigusr1
@itemx sigusr2
These events are generated when the Emacs process receives
the signals @code{SIGUSR1} and @code{SIGUSR2}. They contain no
additional data because signals do not carry additional information.
To catch a user signal, bind the corresponding event to an interactive
command in the @code{special-event-map} (@pxref{Active Keymaps}).
The command is called with no arguments, and the specific signal event is
available in @code{last-input-event}. For example:
(defun sigusr-handler ()
(message "Caught signal %S" last-input-event))
(define-key special-event-map [sigusr1] 'sigusr-handler)
@end example
To test the signal handler, you can make Emacs send a signal to itself:
(signal-process (emacs-pid) 'sigusr1)
@end example
@end table
If one of these events arrives in the middle of a key sequence---that
......@@ -2634,8 +2653,9 @@ These events do, however, appear in @code{last-input-event} immediately
after they are read, and this is the way for the event's definition to
find the actual event.
The events types @code{iconify-frame}, @code{make-frame-visible} and
@code{delete-frame} are normally handled in this way. The keymap which
The events types @code{iconify-frame}, @code{make-frame-visible},
@code{delete-frame}, @code{drag-n-drop}, and user signals like
@code{sigusr1} are normally handled in this way. The keymap which
defines how to handle special events---and which events are special---is
in the variable @code{special-event-map} (@pxref{Active Keymaps}).
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