Pass extra parameters to event

Question

I want to pass three extra parameters to the event :

geocodeService.GeocodeCompleted += new EventHandler<GeocodeService.GeocodeCompletedEventArgs>(geocodeService_GeocodeCompleted);

The parameters are

int id
string color
double heading

    private void Geocode(string strAddress, int waypointIndex, int id, string color, double heading)
    {

        // Create the service variable and set the callback method using the GeocodeCompleted property.
        GeocodeService.GeocodeServiceClient geocodeService = new GeocodeService.GeocodeServiceClient("BasicHttpBinding_IGeocodeService");

        // NEED TO PASS id, color, heading TO THIS EVENT HANDLER
        geocodeService.GeocodeCompleted += new EventHandler<GeocodeService.GeocodeCompletedEventArgs>(geocodeService_GeocodeCompleted);

        GeocodeService.GeocodeRequest geocodeRequest = new GeocodeService.GeocodeRequest();
        geocodeRequest.Credentials = new Credentials();
        geocodeRequest.Credentials.ApplicationId = ((ApplicationIdCredentialsProvider)BingMap.CredentialsProvider).ApplicationId;
        geocodeRequest.Query = strAddress;
        geocodeService.GeocodeAsync(geocodeRequest, waypointIndex);
    }

    private void geocodeService_GeocodeCompleted(object sender, GeocodeService.GeocodeCompletedEventArgs e)
    {
        GeocodeResult result = null;

        if (e.Result.Results.Count > 0)
        {
            result = e.Result.Results[0];
            if (result != null)
            {
                // this.ShowMarker(result);
                this.ShowShip(result);

            }
        }

    }

Vulpes · Answer

Unless you have access to the source code of the class in which the event is defined (which I'd imagine you don't have here) then you can't add extra parameters to an eventhandler for that event. This is because to do this you'd need to be able to change the type of the underlying delegate and the method which fires the event. However what you can do is to make the 3 extra parameters into fields of the class in which the eventhandler is defined so that the code in that handler will have access to their current values: // add these fields private int id; private string color; private double heading; private void Geocode(string strAddress int waypointIndex int id string color double heading) { // Create the service variable and set the callback method using the GeocodeCompleted property. GeocodeService.GeocodeServiceClient geocodeService = new GeocodeService.GeocodeServiceClient(BasicHttpBinding_IGeocodeService); // NEED TO PASS id color heading TO THIS EVENT HANDLER geocodeService.GeocodeCompleted += new EventHandler (geocodeService_GeocodeCompleted); this.id = id; this.color = color; this.heading = heading; GeocodeService.GeocodeRequest geocodeRequest = new GeocodeService.GeocodeRequest(); geocodeRequest.Credentials = new Credentials(); geocodeRequest.Credentials.ApplicationId = ((ApplicationIdCredentialsProvider)BingMap.CredentialsProvider).ApplicationId; geocodeRequest.Query = strAddress; geocodeService.GeocodeAsync(geocodeRequest waypointIndex); } private void geocodeService_GeocodeCompleted(object sender GeocodeService.GeocodeCompletedEventArgs e) { // this evenhandler now has access to the id color and heading fields GeocodeResult result = null; if (e.Result.Results.Count > 0) { result = e.Result.Results[0]; if (result != null) { // this.ShowMarker(result); this.ShowShip(result); } } }