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XtAppAddSignal(3) Library Functions Manual XtAppAddSignal(3) NAME XtAppAddSignal, XtRemoveSignal, XtNoticeSignal - register and remove a signal source SYNTAX XtSignalId XtAppAddSignal(XtAppContext app_context, XtSignalCallback- Proc 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 XtAppAdd- Signal 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 operat- ing system dependent signal handler the application may call XtAppAdd- Signal 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 XtAppAdd- Signal. 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 be- fore 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 ALSO XtAppAddTimeOut(3),XtAppAddInput(3),XtAppAddWorkProc(3) X Toolkit Intrinsics - C Language Interface Xlib - C Language X Interface XT FUNCTIONS X Version 11 XtAppAddSignal(3)