XtAppAddSignal(3Xt)X Version 11 (Release 6.6) 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
          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(3Xt),XtAppAddInput(3Xt),XtAppAddWorkProc(3Xt)
          X Toolkit Intrinsics - C Language Interface
          Xlib - C Language X Interface


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