C＃繼承：當我調用派生類構造函數時，如何調用基類構造函數

Question

我試圖弄清楚當我調用派生類構造函數時如何調用基類構造函數。

我有一個名為“AdditionalAttachment”的類，它繼承自System.Net.Mail.Attachment。我已經為我的新類添加了2個屬性，以便我可以使用我的新屬性獲得現有Attachment類的所有屬性

public class AdditionalAttachment: Attachment
{
   [DataMember]
   public string AttachmentURL
   {
       set;
       get;
   }
   [DataMember]
   public string DisplayName
   {
       set;
       get;
   }
}

之前我曾經創建過類似的構造函數

// objMs是一個MemoryStream對象

Attachment objAttachment = new Attachment(objMs, "somename.pdf")

我想知道如何為我的類創建相同類型的構造函數，它將執行與基類的上述構造函數相同的操作

Answer 1

這會將您的參數傳遞給基類的構造函數：

public AdditionalAttachment(MemoryStream objMs, string displayName) : base(objMs, displayName)
{
   // and you can do anything you want additionally 
   // here (the base class's constructor will have 
   // already done its work by the time you get here)
}

Answer 2

您可以編寫一個調用類基構造函數的構造函數：

public AdditionalAttachment(MemoryStream objMs, string filename)
    : base(objMs, filename)
{
}

Answer 3

使用此功能：

public AdditionalAttachment(MemoryStream ms, string name, etc...)
       : base(ms, name) 
{
}

Answer 4

public class AdditionalAttachment: Attachment
{
   public AdditionalAttachment(param1, param2) : base(param1, param2){}
   [DataMember]
   public string AttachmentURL
   {
       set;
       get;
   }
   [DataMember]
   public string DisplayName
   {
       set;
       get;
   }
}