c# - C# 将额外参数传递给事件

Question

我想向事件传递三个额外的参数：

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

参数是

• 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);
  
  
          }
      }
  
  }
  

Answer 1

它看起来像GeocodeCompletedEventArgs延伸AsyncCompletedEventArgs。AsyncCompletedEventArgs具有UserState可用于存储异步事件状态信息的属性。此状态通常作为参数传递给引发事件的方法。

有关更多信息，请参阅此问题：Bing GeocodeService userState usage as custom additional parameter

Answer 2

您可以扩展 GeocodeService.GeocodeServiceClient 添加这些属性，然后在事件方法 geocodeService_GeocodeCompleted 中使用 sender 参数：

var service = (GeocodeService.GeocodeServiceClient) sender;

快速而肮脏（恕我直言）的版本是使用 lambda 表达式：

将参数传递给 EventHandler