
    <<DifferenceAveragers.Mesa>>
        <<Spreitzer, June 17, 1986 2:38:28 pm PDT>>

    DIRECTORY Rope, ViewerClasses;

    DifferenceAveragers: CEDAR DEFINITIONS = {

        ROPE: TYPE = Rope.ROPE;
        Viewer: TYPE = ViewerClasses.Viewer;

        Seconds: TYPE = INT;

        Averager: TYPE = REF AveragerPrivate;
        AveragerPrivate: TYPE;

        Create: PROC
            [
                viewerInfo: ViewerClasses.ViewerRec _ [],
                samplePeriod, halfLife: Seconds,
                logMin, logMax: INT,
                Sample: PROC [clientData: REF ANY] RETURNS [add, subtract: REAL],
                clientData: REF ANY _ NIL
                ]
            RETURNS [Averager];

        AsViewer: PROC [Averager] RETURNS [Viewer];

        GetLayout: PROC [a: Averager, ancestor: Viewer] RETURNS [samplePeriodButton, halfLifeButton, bars: XRange --in client coords of 
        ancestor (screen if NIL)--];
            XRange: TYPE = RECORD [left, width: INTEGER];

        }.