代表们有哪些优势？ [英] What are the advantages of delegates?

问题描述

使用代表的好处和好处是什么？任何人都可以提供任何简单的例子？

What are the benefits/advantages of using delegates? Can anyone provide any simple examples?

推荐答案

他们是封装一段代码的好方法。例如，当您将一个事件处理程序附加到按钮时，该处理程序是一个委托。该按钮不需要知道它是什么，只是在正确的时间调用它。

They're a great way of encapsulating a piece of code. For instance, when you attach an event handler to the button, that handler is a delegate. The button doesn't need to know what it does, just how to call it at the right time.

另一个例子是LINQ - 过滤，投影等都需要相同一种模板代码;所有这些更改是表示过滤器，投影等的逻辑。使用C＃3中的lambda表达式（将其转换为代表或表达式树），这使得它非常简单：

Another example is LINQ - filtering, projecting etc all require the same kind of template code; all that changes is the logic to represent the filter, the projection etc. With lambda expressions in C# 3 (which are converted into delegates or expression trees) this makes it really simple:

var namesOfAdults = people.Where(person => person.Age >= 18)
                          .Select(person => person.Name);

（也可以表示为查询表达式，但让我们不要偏离委托人太远）

(That can also be represented as a query expression, but let's not stray too far from delegates.)

代理的另一种思考方式是单一方法接口类型。例如， EventHandler 委托类型有点像：

Another way of thinking of a delegate is as a single-method interface type. For example, the EventHandler delegate type is a bit like:

public interface IEventHandler
{
    void Invoke(object sender, EventArgs e)
}

但是框架中的委托支持允许将代理链接在一起，异步调用，用作事件处理程序等。

But the delegate support in the framework allows delegates to be chained together, invoked asynchronously, used as event handlers etc.

有关代理和事件的更多信息，请参阅我的主题文章。它的重点是事件，但它也包括代表。

For more on delegates and events, see my article on the topic. Its focus is events, but it covers delegates too.

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