示例：加快反射API与委托的.NET / C＃ [英] Example : Speeding up Reflection API with delegate in .NET/C#

问题描述

由于被要求在此<一个href="http://stackoverflow.com/questions/6430479/speeding-up-reflection-api-with-delegate-in-net-c/6430561#6430561">post,我想出了一个使用委派用来加快恢复体力的.NET / C＃的例子。

As is asked in this post, I came up with an example that uses Delegate to speedup Refection in .NET/C#.

不过，我运行的时候得到这个错误（编译正常工作）。可能是什么问题？

However, I got this error when running (compilation works fine). What might be wrong?

Unhandled Exception: System.ArgumentException: type is not a subclass of Multicastdelegate
  at System.Delegate.CreateDelegate (System.Type type, System.Object firstArgument, System.Reflection.MethodInfo method, Boolean throwOnBindFailure, Boolean allowClosed) [0x00000] in <filename unknown>:0 
  at System.Delegate.CreateDelegate (System.Type type, System.Reflection.MethodInfo method, Boolean throwOnBindFailure) [0x00000] in <filename unknown>:0 
  at System.Delegate.CreateDelegate (System.Type type, System.Reflection.MethodInfo method) [0x00000] in <filename unknown>:0 
  at EX.RefTest.DelegateTest () [0x00000] in <filename unknown>:0 
  at EX.RefTest.Main () [0x00000] in <filename unknown>:0 

ADDED

这是（工作）来源$ C ​​$ C得益于乔恩和放大器的帮助; ChaosPandion。

ADDED

This is the (working) source code thanks to the help from Jon & ChaosPandion.

using System.Reflection;
using System;

namespace EX
{
    public class Hello
    {
        // properties
        public int Valx {get; set;}
        public int Valy {get; set;}
        public Hello()
        {
            Valx = 10; Valy = 20;
        }
        public int Sum(int x, int y)
        {
            Valx = x; Valy = y;
            return (Valx + Valy);
        }
    }
    public class RefTest
    {
        static void DelegateTest()
        {
            Hello h = new Hello();
            Type type = h.GetType();
            MethodInfo m = type.GetMethod("Sum");

            // Wrong! Delegate call = Delegate.CreateDelegate(type, m);
            Delegate call = Delegate.CreateDelegate(typeof(Func<int, int, int>), h, m);
            int res = (int) call.DynamicInvoke(new object[] {100, 200});
            Console.WriteLine("{0}", res);
            // This is a direct method implementation from Jon's post, and this is much faster
            Func<int, int, int> sum = (Func<int, int, int>) Delegate.CreateDelegate(typeof(Func<int, int, int>), h, m);
            res = sum(100, 200);
            Console.WriteLine("{0}", res);
        }
        static void Main()
        {
            DelegateTest();
        }
    }
}

ADDED2

基于乔恩的答案

，我做了一些性能测试使用的总和1000倍。 相较于使用的方法（INT）call.DynamicInvoke（新对象[] {100，200}）; ， Func键＆LT; INT，INT， INT＆GT;总和=（Func键＆LT; INT，INT，INT＆GT;）Delegate.CreateDelegate（typeof运算（Func键＆LT; INT，INT，INT＆GT;），H，M）; 快300倍。

ADDED2

Based on Jon's answer, I did some performance test to use sum 1000 time. Compared to the method of using (int) call.DynamicInvoke(new object[] {100, 200});, Func<int, int, int> sum = (Func<int, int, int>) Delegate.CreateDelegate(typeof(Func<int, int, int>), h, m); is 300 times faster.

推荐答案

您好不是委托类型 - 所以你不能将它传递到 Delegate.CreateDelegate 作为第一个参数。您需要使用相同的参数类型和返回类型的委托类型 - 在这种情况下，是这样的：

Hello isn't a delegate type - so you can't pass it into Delegate.CreateDelegate as the first argument. You need a delegate type with the same parameter types and return type - in this case, something like:

delegate int Foo(int x, int y);

或

Func<int, int, int>

另外请注意， Delegate.CreateDelegate 您已经叫过载，就是要用于的静态的方法 - 你应该利用过载也采取了委托的目标（在这种情况下， ^ h ）。

Also note that the overload of Delegate.CreateDelegate you've called is meant to be used for a static method - you ought to be using the overload which also takes the target of the delegate (in this case, h).

我有一个博客文章这说明使用 Delegate.CreateDelegate 加快访问。请注意，我不希望 DynamicInvoke 比直接用反射调用方法显著快......它仍然将不得不检查等，真的是你想要的参数类型一个叫做静态强类型委托类型（而不是动态），以使事情变得真快。

I have a blog post which shows using Delegate.CreateDelegate for speeding up access. Note that I wouldn't expect DynamicInvoke to be significantly faster than calling the method directly with reflection... it's still going to have to check the parameter types etc. Really you want a strongly-typed delegate type called statically (as opposed to dynamically) to make things really fast.

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