XtAppAddSignal(3Xt) XT FUNCTIONS XtAppAddSignal(3Xt)NAME
XtAppAddSignal, XtRemoveSignal, XtNoticeSignal - register
and remove a signal source
SYNTAX
XtSignalId XtAppAddSignal(app_context, proc, client_data)
XtAppContext app_context;
XtSignalCallbackProc proc;
XtPointer client_data;
void XtRemoveSignal(id)
XtSignalId id;
void XtNoticeSignal(id)
XtSignalId id)
ARGUMENTS
app_context
Specifies the application context.
client_data
Specifies the argument that is to be passed to
the specified procedure when a signal has been
raised.
id Specifies the ID returned from the corresponding
XtAppAddSignal call.
proc Specifies the procedure that is to be called
when the signal has been raised.
DESCRIPTION
The XtAppAddSignal function initiates a mechanism for han-
dling signals within the context of the Intrinsics. Prior
to establishing an operating system dependent signal han-
dler the application may call XtAppAddSignal and store the
returned id in a place accessible to the signal handler.
Upon receipt of a signal from the operating system, the
application may call XtNoticeSignal passing the id
returned by the call to XtAppAddSignal.
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 callback 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 speci-
fied Intrinsics signal handler. The client should disable
X Version 11 Release 6.4 1
XtAppAddSignal(3Xt) XT FUNCTIONS XtAppAddSignal(3Xt)
the source of the signal before calling XtRemoveSignal.
SEE ALSOXtAppAddTimeOut(3Xt),XtAppAddInput(3Xt),XtAppAd-
dWorkProc(3Xt)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface
X Version 11 Release 6.4 2