删除事件处理程序 [英] Removing event handlers

问题描述

这是：

  Button.Click  -  = new EventHandler（Button_Click）; 
  

与此相同：

  Button.Click  -  = Button_Click; 
  

我问，因为对我来说，似乎前者正在删除对方法的新引用，后一种方法本身就是去除一个方法。但是，再一次，也许新的EventHandler部分是隐含在+ =或 - =重载的情况下，程序员没有明确赋值呢？

如果不同于

  Button.Click  -  = new EventHandler（Button_Click）; 
  

VS

  Button.Click  -  = Button_Click; 
  

谢谢。

解决方案

这是一样的。第二个仅仅是第一个的句法糖，而对于代表类型，相等的比较被适当地重载：

两个同样类型的代理与相同的目标，方法和调用列表被认为是相等的。

资料来源： MSDN，Delegate.Equality Operator

Is this:

Button.Click -= new EventHandler(Button_Click);

the same as this:

Button.Click -= Button_Click;

I ask because to me it seems that the former is removing a new reference to a method, and the latter one is removing a method itself. But then again, maybe the new EventHandler part is implicit in the += or -= overload in case the programmer doesn't explicitly assign it like that?

In case it is different how about

Button.Click -= new EventHandler(Button_Click);

VS

Button.Click -= Button_Click;

Thanks.

解决方案

It is the same. The second is merely syntactic sugar for the first, and equality comparison is overloaded appropriately for delegate types:

Two delegates of the same type with the same targets, methods, and invocation lists are considered equal.

Source: MSDN, Delegate.Equality Operator

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