XtAppAddSignal(3Xt)XtAppAddSignal(3Xt)NAME
XtAppAddSignal, XtRemoveSignal, XtNoticeSignal - register and remove a
signal source
SYNOPSIS
XtSignalId XtAppAddSignal(app_context, proc, client_data)
XtAppContext app_context;
XtSignalCallbackProc proc;
XtPointer client_data;
void XtRemoveSignal(id)
XtSignalIdid;
void XtNoticeSignal(id)
XtSignalId id;
ARGUMENTS
Specifies the application context. Specifies the argument that is to
be passed to the specified procedure when a signal has been raised.
Specifies the ID returned from the corresponding XtAppAddSignal call.
Specifies the procedure that is to be called when the signal has been
raised.
DESCRIPTION
The XtAppAddSignal function initiates a mechanism for handling signals
within the context of the Intrinsics. Prior to establishing an operat‐
ing system dependent signal handler the application may call XtAp‐
pAddSignal and store the returned id in a place accessible to the sig‐
nal handler.
Upon receipt of a signal from the operating system, the application may
call XtNoticeSignal passing the id returned by the call to XtAppAddSig‐
nal.
XtNoticeSignal is the only Intrinsics function that can safely be
called from a signal handler. If XtNoticeSignal is called multiple
times before the Intrinsics are able to invoke the registered callback,
the callback is only called once. Logically the Intrinsics maintain
“pending” for each registered callback. This flag is initially False
and is set to True by XtNoticeSignal; the Intrinsics invoke the call‐
back whenever the flag is True, and the flag is set to False just
before the callback is invoked.
The XtRemoveSignal function is called to remove the specified Intrin‐
sics signal handler. The client should disable the source of the signal
before calling XtRemoveSignal.
SEE ALSOXtAppAddTimeOut(3Xt), XtAppAddInput(3Xt), XtAppAddWorkProc(3Xt),
X Toolkit Intrinsics -- C Language Interface
Xlib -- C Language X Interface
XtAppAddSignal(3Xt)
