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queryInterrupt - interrupt a computation in OpenMaple
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Calling Sequence
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queryInterrupt(data)
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Parameters
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data
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user_data pointer passed to StartMaple ()
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Description
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The queryInterrupt function allows the user to halt computation. This function is called before each Maple statement is executed. In general, this occurs hundreds of times per second. For some operations (notably large integer manipulations), the queryInterrupt function is called only every few seconds.
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The prototype for the function that you can assign to the entry in the MapleCallBack must look like the following.
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Function QueryInterrupt(ByVal data As Long) As Long
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To halt the computation, the function must return True. To continue the computation, the function must return False.
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The data parameter contains the same data as passed to StartMaple in the user_data parameter.
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Examples
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Public ShouldStop As Boolean
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ShouldStop = False
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Public Function QueryInterrupt(ByVal data As Long) As Long
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If ShouldStop Then
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MainForm.StopButton.Caption = "Stop"
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ShouldStop = False
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QueryInterrupt = True
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Else
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QueryInterrupt = False
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End If
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End Function
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Private Sub StopButton_Click()
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If Screen.MousePointer = vbHourglass Then
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ShouldStop = True
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StopButton.Caption = "Stopping ..."
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End If
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End Sub
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' assignment to MapleCallback entry
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cb.lpQueryInterrupt = GetProc(AddressOf QueryInterrupt)
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' test statement that will invoke the CallBackCallBack
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EvalMapleStatement kv, "do end do;" 'infinite loop
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See Also
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callBackCallBack, errorCallBack, OpenMaple, OpenMaple/VB/API, OpenMaple/VB/Examples, readLineCallBack, redirectCallBack, StartMaple, statusCallBack, streamCallBack, textCallBack
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Download Help Document
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