有没有委托这不是一个MulticastDelegate在C＃中？ [英] Is there a Delegate which isn't a MulticastDelegate in C#?

问题描述

我想答案是否定？如果没有，为什么我们已经分居代理和 MulticastDelegate 班？也许是因为一些其他.NET语言？

I think the answer is NO? If there isn't, why do we have separated Delegate and MulticastDelegate classes? Maybe it's again because of "some other .NET languages"?

推荐答案

编辑：我的认为的，这是ECMA 335的一部分，但我看不出它有任何地方

I thought this was part of ECMA 335, but I can't see it in there anywhere.

您不能创建在C＃这样的委托类型，但你可以在IL：

You can't create such a delegate type in C#, but you can in IL:

.class public auto ansi sealed Foo
       extends [mscorlib]System.Delegate
{
    // Body as normal
}

C＃编译器具有使用这样的代表没有问题：

The C# compiler has no problems using such a delegate:

using System;

class Test
{
    static void Main()
    {
        Foo f = x => Console.WriteLine(x);
        f("hello");
    }
}

但CLR，当它试图加载它：

But the CLR does when it tries to load it:

未处理的异常：System.TypeLoadException：未能从程序集富，版本= 0.0.0.0，文化=中性公钥=空'加载类型'富'，因为它不能直接从委托类继承。      在Test.Main（）

Unhandled Exception: System.TypeLoadException: Could not load type 'Foo' from assembly 'Foo, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' because it cannot inherit directly from the delegate class. at Test.Main()

基本上代表/ MulticastDelegate分离是一种历史的偶然。我相信，早期的alpha / beta版本并进行区分，但事实证明这太混乱，一般没有什么用处 - 所以现在的每次的代表从MulticastDelegate派生

Basically the Delegate/MulticastDelegate separation is an historical accident. I believe that early alpha/beta versions did make the distinction, but it proved too confusing and generally not useful - so now every delegate derives from MulticastDelegate.

（有趣的是，C＃的规范只提到MulticastDelegate一次，在不能被用作通用的约束的类型列表。）

(Interestingly, the C# specification only mentions MulticastDelegate once, in the list of types which can't be used as generic constraints.)

这篇关于有没有委托这不是一个MulticastDelegate在C＃中？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！