XtAppAddSignal(3) XT FUNCTIONS XtAppAddSignal(3)

NAME

XtAppAddSignal, XtRemoveSignal, XtNoticeSignal - register and remove
a signal source

SYNTAX

XtSignalId XtAppAddSignal(XtAppContext app_context,
XtSignalCallbackProc proc, XtPointer client_data);

void XtRemoveSignal(XtSignalId id);

void XtNoticeSignal(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 handling
signals within the context of the Intrinsics. Prior to establishing
an operating system dependent signal handler 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 specified
Intrinsics signal handler. The client should disable the source of
the signal before calling XtRemoveSignal.

SEE ALSO

XtAppAddTimeOut(3),XtAppAddInput(3),XtAppAddWorkProc(3)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface

X Version 11 libXt 1.1.5 XtAppAddSignal(3)