如何將參數傳遞給ElapsedEventHandler調用的函數？

Question

如何參數傳遞給由ElapsedEventHandler調用的函數？

我的代碼：

private static void InitTimer(int Index) 
{ 
    keepAlive[Index] = new Timer(); 
    keepAlive[Index].Interval = 3000; 
    keepAlive[Index].Elapsed += new ElapsedEventHandler(keepAlive_Elapsed[, Index]); 
    keepAlive[Index].Start(); 
} 

public static void keepAlive_Elapsed(object sender, EventArgs e[, int Index]) 
{ 

    PacketWriter writer = new PacketWriter(); 
    writer.AppendString("KEEPALIVE|.\\"); 
    ServerSocket.Send(writer.getWorkspace(), Index); 
    ServerSocket.DisconnectSocket(Index); 
} 

我想要做的是括號（[和]）。 但只是這樣做，顯然不工作...

Answer 1

你不能在方法本身內做到這一點 - 你必須使你的事件處理程序有效地意識到它的上下文。這樣做的簡單的方法是用一個lambda表達式或匿名方法：

private static void InitTimer(int Index) 
{ 
    keepAlive[Index] = new Timer(); 
    keepAlive[Index].Interval = 3000; 
    keepAlive[Index].Elapsed += delegate { KeepAliveElapsed(Index); }; 
    keepAlive[Index].Start(); 
} 

public static void KeepAliveElapsed(int Index) 
{  
    PacketWriter writer = new PacketWriter(); 
    writer.AppendString("KEEPALIVE|.\\"); 
    ServerSocket.Send(writer.getWorkspace(), Index); 
    ServerSocket.DisconnectSocket(Index); 
} 

這裏，匿名方法（與delegate關鍵字的比特）已經創建了所知道的Index參數InitTimer委託。它只是調用KeepAliveElapsed方法。我使用了匿名方法語法，因爲您不需要發件人或事件參數;如果你沒有需要他們，我可能會使用一個lambda表達式來代替，如

private static void InitTimer(int Index) 
{ 
    keepAlive[Index] = new Timer(); 
    keepAlive[Index].Interval = 3000; 
    keepAlive[Index].Elapsed += (sender, args) => KeepAliveElapsed(sender, Index); 
    keepAlive[Index].Start(); 
} 

public static void KeepAliveElapsed(object sender, int Index) 
{  
    PacketWriter writer = new PacketWriter(); 
    writer.AppendString("KEEPALIVE|.\\" + sender); 
    ServerSocket.Send(writer.getWorkspace(), Index); 
    ServerSocket.DisconnectSocket(Index); 
} 

（需要注意的是傳統的Index參數應該叫index，順便說一句。）