1XtAppAddSignal(3)                XT FUNCTIONS                XtAppAddSignal(3)
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NAME

6       XtAppAddSignal, XtRemoveSignal, XtNoticeSignal - register and remove a
7       signal source
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SYNTAX

10       #include <X11/Intrinsic.h>
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12       XtSignalId XtAppAddSignal(XtAppContext app_context, XtSignalCallback‐
13              Proc proc, XtPointer client_data);
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15       void XtRemoveSignal(XtSignalId id);
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17       void XtNoticeSignal(XtSignalId id);
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ARGUMENTS

20       app_context
21                 Specifies the application context.
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23       client_data
24                 Specifies the argument that is to be passed to the specified
25                 procedure when a signal has been raised.
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27       id        Specifies the ID returned from the corresponding XtAppAdd‐
28                 Signal call.
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30       proc      Specifies the procedure that is to be called when the signal
31                 has been raised.
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DESCRIPTION

34       The XtAppAddSignal function initiates a mechanism for handling signals
35       within the context of the Intrinsics.  Prior to establishing an operat‐
36       ing system dependent signal handler the application may call XtAppAdd‐
37       Signal and store the returned id in a place accessible to the signal
38       handler.
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40       Upon receipt of a signal from the operating system, the application may
41       call XtNoticeSignal passing the id returned by the call to XtAppAdd‐
42       Signal.
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44       XtNoticeSignal is the only Intrinsics function that can safely be
45       called from a signal handler.  If XtNoticeSignal is called multiple
46       times before the Intrinsics are able to invoke the registered callback,
47       the callback is only called once.  Logically the Intrinsics maintain
48       “pending” for each registered callback.  This flag is initially False
49       and is set to True by XtNoticeSignal; the Intrinsics invoke the call‐
50       back whenever the flag is True, and the flag is set to False just be‐
51       fore the callback is invoked.
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53       The XtRemoveSignal function is called to remove the specified Intrin‐
54       sics signal handler.  The client should disable the source of the sig‐
55       nal before calling XtRemoveSignal.
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SEE ALSO

58       XtAppAddTimeOut(3),XtAppAddInput(3),XtAppAddWorkProc(3)
59       X Toolkit Intrinsics - C Language Interface
60       Xlib - C Language X Interface
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64X Version 11                      libXt 1.2.1                XtAppAddSignal(3)
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