Encapsulate Google Map V.3 event to listen object methods

I want to encapsulate google map polygon(google.maps.Polygon) and map (google.maps.Map) into a javascript object and handle some event for both polygon and map. Here is some code

function Landmark(map, polygon) {
    this.map = map;
    this.polygon = polygon;

    // Add a listener for the click event
    google.maps.event.addListener(this.map, 'click', this.addPoint);
    google.maps.event.addListener(this.polygon, 'click', this.addPoint);

    addPoint = function (event) {
        alert("xxx");
    }
}

I called the function using :

var myLatLng = new google.maps.LatLng(24.886436490787712, -70.2685546875);
    var myOptions = {
                        zoom: 5,
                        center: myLatLng,
                        mapTypeId: google.maps.MapTypeId.TERRAIN
                    };

    map = new google.maps.Map(document.getElementById("map_canvas"), myOptions);

    polygonInTest = new google.maps.Polygon({
                                                strokeColor: "#FF0000",
                                                strokeOpacity: 0.8,
                                                strokeWeight: 2,
                                                fillColor: "#FF0000",
                                                fillOpacity: 0.35
                                            });

    polygonInTest.setMap(map);

    var landmark = new Landmark(map, polygonInTest);

But when I trigger the event, by clicking the 开发者_C百科map, I got this error from firebug :

f.e is undefined
[Break On This Error] function de(a,b){var c,d=a.__e3_||{};i...n"+b]=c,c=new ce(a,b,c,3));return c}; 

Can anyone point me where have I done wrong and give some suggestions? Any comment or help is appreciated.

Thanks in advance.

---

My best guess is that when you are creating an event listener

google.maps.event.addListener(this.map, 'click', this.addPoint);

your handler is not yet defined (i.e. you define addPoint later), so at the time of addListener() call this.addPoint is undefined. And GMaps messes up later when the time comes for the handler to be called.

At least that's how I realized I had a problem at this point by looking at your code :)