为什么使用匿名委托声明此事件？

Question

I have seen people define their events like this:

public event EventHandler<EventArgs> MyEvent = delegate{};

Can somebody explain how this is different from defining it without it? Is it to avoid checking for null when raising the event?

Answer 1

You got it - adding the empty delegate lets you avoid this:

public void DoSomething() { 
    if (MyEvent != null) // Unnecessary! 
        MyEvent(this, "foo"); 
} 

Answer 2

此声明确保MyEvent永远不为null，从而消除了每次都必须检查null的繁琐且容易出错的任务，每次触发事件时都要执行额外的空委托。