使用引用匿名代理的「this」

Question

如何使用引用委託實例而不是類實例的this（或其他類型的東西）？

instance.OnEventFoo += delegate() 
    { 
     if (condition) 
     { 
      instance.OnEventBar += this; 
     } 
    }; 

Answer 1

既然你不能引用它宣告前一個變量，你必須：

1. 首先聲明變量，
2. 然後指定一個代表，
3. 再註冊事件處理程序。

---

// Add an anonymous delegate to the events list and auto-removes automatically if item disposed 
DataRowChangeEventHandler handler = null; 
handler = (sender, args) => 
    { 
     if (condition) 
     { 
      // need to remove this delegate instance of the events list 
      RowChanged -= handler; 
     } 
    }; 

something.RowChanged += handler; 

Answer 2

您需要將其存儲在一個變量的地方。例如：

EventHandler rowChanged = null; // to avoid "uninitialized variable" error 

rowChanged = (s, e) => 
{ 
    if (condition) 
    { 
     // this will unsubscribe from the event as expected 
     RowChanged -= rowChanged; 
    } 
};