使用“this”引用匿名代表

Question

如何使用this（或类似的东西）引用委托实例而不是类实例？

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

Answer 1

由于在声明变量之前无法引用变量，因此必须：

1. 首先声明变量
2. 然后分配一名代表，
3. 然后使用事件注册处理程序。

---

// 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

您需要将其存储在某个变量中。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;
    }
};