这是什么C＃code以＆QUOT;箭头QU​​OT;意思是，它是怎么叫？ [英] What does this C# code with an "arrow" mean and how is it called?

问题描述

我想在我的C＃的客户端程序启用SSL，发现如下code <一个href="http://stackoverflow.com/questions/1742938/wcf-could-not-establish-trust-relationship-for-the-ssl-tls-secure-channel-with/1742967#1742967">in这个答案：

  System.Net.ServicePointManager.ServerCertificateValidationCallback + =
    （SE，证书，链，sslerror）=＆GT;
    {
        返回true;
    };
 

我增加了code到我的程序，它解决了这个问题，但我完全不明白究竟怎么了它的工作原理。

左侧部分 System.Net.ServicePointManager.ServerCertificateValidationCallback 一些回调 + = 修改了回调。但什么是剩余的结构是什么意思？我花了20分钟寻找到至少发现它是如何正确地调用，并在那里我可以找到如何读取更多的信息，但一切都是徒劳。我想这是主题相关的LINQ和搜索LINQ箭头，但没有发现任何合理的。

这是怎么回事（胡说，胡说，胡说）=＆GT; {返回true;} 结构打来电话，我在哪里可以找到这种结构的详细信息。

解决方案

这是一个lambda EX pression。这是一个非常特殊的匿名委托。基本上，你要定义一个方法，而不是给一个名字。它的参数是左边的 =＆GT; 和方法体是右侧的 =＆GT; 。在特定的情况下，

 （SE，证书，链，sslerror）=＆GT; {返回true; };
 

是一个lambda EX pression定义一个匿名方法。这种特殊的方法有四个参数

 对象本身
x509证书证书
X509Chain链
SslPolicyErrors sslerror
 

和方法体为

 返回true;
 

这是因为如果你说的

 类ServerCertificateValidation {
    公共BOOL OnRemoteCertificateValidation（
        对象本身，
        X509证书证书，
        X509Chain链，
        SslPolicyErrors sslerror
    ）{
        返回true;
    }
}
 

然后

  VAR验证=新ServerCertificateValidation（）;
System.Net.ServicePointManager.ServerCertificateValidationCallback + =
    validation.OnRemoteCertificateValidation;
 

  

这是怎么回事（胡说，胡说，胡说）=＆GT; {返回true;} 结构打来电话，我在哪里可以找到这种结构的详细信息。

这就是所谓的以相同的方式，任何其它方法被调用。例如，你可以这样做：

  Func键＆LT; INT，INT，INT＆GT;加法器=（M，N）=＆GT; M + N;
 

在这里，我定义一个吃一对 INT ，并返回一个方法的 INT 。 INT 那是通过将输入参数的值来获得。它可以像任何其他方法调用

  INT 4 =加法器（2,2）;
 

下面是对拉姆达EX pressions ，并在一篇文章拉姆达运营商。如果你真的有兴趣，这个名字来自演算。

I was trying to enable SSL in my C# client program and found the following code in this answer:

System.Net.ServicePointManager.ServerCertificateValidationCallback +=
    (se, cert, chain, sslerror) =>
    {
        return true;
    };

I added the code to my program and it solved the problem, but I completely don't get how exactly it works.

The left part System.Net.ServicePointManager.ServerCertificateValidationCallback is some callback and += modifies that callback. But what does the remaining construct mean? I spent 20 minutes searching to at least find how it is properly called and where I can find more info on how to read that, but all in vain. I suppose it is somehow related to LINQ and searched for "LINQ arrow", but didn't find anything reasonable.

How is that (blah,blah,blah)=>{return true;} construct called and where can I find more info on such constructs?

解决方案

That is a lambda expression. It is a very special anonymous delegate. Basically you are defining a method and not giving a name. Its parameters are to the left of the => and the method body is to the right of the =>. In your particular case,

(se, cert, chain, sslerror) => { return true; };

is an anonymous method defined by a lambda expression. This particular method has four parameters

object se
X509Certificate cert
X509Chain chain
SslPolicyErrors sslerror

and the method body is

return true;

It's as if you had said

class ServerCertificateValidation {
    public bool OnRemoteCertificateValidation(
        object se,
        X509Certificate cert,
        X509Chain chain,
        SslPolicyErrors sslerror
    ) {
        return true;
    }
}

and then

var validation = new ServerCertificateValidation();
System.Net.ServicePointManager.ServerCertificateValidationCallback +=
    validation.OnRemoteCertificateValidation;

How is that (blah,blah,blah)=>{return true;} construct called and where can I find more info on such constructs?

It's called the same way that any other method is called. For example, you can do this:

Func<int, int, int> adder = (m, n) => m + n;

Here I am defining a method that eats a pair of int and returns an int. That int is obtained by adding the values of the input parameters. It can be invoked like any other method.

int four = adder(2, 2); 

Here's an article on MSDN on lambda expressions and an article on the lambda operator. If you're really interested, the name comes from lambda calculus.

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