在虛函數中拋出異常是否是一種好的做法？

即使解決方案如此明顯，我應該從未發佈過這個消息，我將其作爲提醒和對其他人的參考。在虛函數中拋出異常是否是一種好的做法？

我有以下基本類：

using System; 

namespace LibraryWPF 
{ 
    public class Library 
    { 
     /// <summary> 
     /// Event fired when content is added to the libary 
     /// </summary> 
     public event EventHandler<ObjectInfoEventArgs> Library_ObjectAdded; 

     /// <summary> 
     /// Event fired when the scan of the library is finished 
     /// </summary> 
     public event EventHandler Library_Finished; 

     // Properties 

     /// <summary> 
     /// Whether to stop checking the library or not 
     /// </summary> 
     public bool Stop 
     { 
      get; 
      set; 
     } 

     /// <summary> 
     /// Where to look for content 
     /// </summary> 
     public string Root 
     { 
      get; 
      set; 
     } 

     /// <summary> 
     /// Empty instance of library's object for reflection 
     /// </summary> 
     public virtual object ObjectInfo 
     { 
      get 
      { 
       // Should this raise as exception to show if it's not been overridden? 
       return null; 
      } 
     } 

     /// <summary> 
     /// Sub class overrides this method to call it's actual find code 
     /// </summary> 
     public virtual void Find() 
     { 
      // Should this raise as exception to show if it's not been overridden? 
     } 

     /// <summary> 
     /// Build the library 
     /// </summary> 
     public void Build() 
     { 
      if (Root != null && Root.Length > 0) 
      { 
       Stop = false; 
       Find(); 
      } 

      // Final update 
      if (Library_Finished != null) 
      { 
       Library_Finished(this, null); 
      } 
     } 

     /// <summary> 
     /// Sub class calls this method to fire the ObjectAdded event 
     /// </summary> 
     /// <param name="objectInfo">Object just added to library</param> 
     protected void OnObjectAdded(object objectInfo) 
     { 
      if (Library_ObjectAdded != null) 
      { 
       Library_ObjectAdded(this, new ObjectInfoEventArgs(objectInfo)); 
      } 
     } 
    } 
}

子類覆蓋ObjectInfo返回對象，他們正在尋找通過使用反射型的實例。他們也覆蓋Find做實際的搜索。

這樣我的應用程序代碼就可以使用基類方法，因此在編譯時它不需要知道有關子類的任何信息。我告訴它使用DI尋找什麼樣的內容。

所以 - 我的問題是這樣的：

我應該拋出一個異常在ObjectInfo基類版本和Find因此，如果子類不正確執行我得到一個運行時錯誤？或者我應該編碼ObjectInfo返回null？

來源

2009-04-27 ChrisF

我不能相信我完全忘了讓方法抽象化。 – ChrisF 2009-04-27 14:50:23