如何动态创建Action< T>在运行时？ [英] How can I dynamically create an Action<T> at runtime?

问题描述

我想在运行时能够等同于以下内容：

I want to be able to do the equivalent to the following at runtime:

var action = new Action<ANYTHING AT RUNTIME>(obj => Console.WriteLine("Called = " + obj));

我知道我需要为Action获取正确的类型，但不知道如何获得最终的使用Delegate.Create。 在Action定义中表示T。

I know I need to get the correct type for the Action, but not sure how to get the final bit using Delegate.Create. Type represent T in the Action definition.

var actionType = typeof(Action<>).MakeGenericType(Type);
var constructor = actionType.GetConstructors()[0];
var @delegate = Delegate.CreateDelegate(actionType, <WHAT GOES HERE>);

人们似乎缺少的一点是我正在尝试创建一个Action的实例，其中T可以没有静态指定，因为它是从属性派生的类中使用的 - 这意味着T可以是任何东西，它不能被定义为通用定义

the point people seem to be missing is I'm trying to create an instance of Action where T can not be specified statically because it is being used from a class derived from Attribute - this means T could be anything and it can not be defines as a generic definition

干杯

Cheers

推荐答案

如果你知道你需要执行的操作是什么，如何执行它，不管类型如何，只需做一个通用的方法来执行操作并创建你的代理方式？

If you know what the operation you need to perform is and how to perform it regardless of type (as in your example) why not just make a generic method that performs the operation and create your delegate that way?

class Program
{
    public static void Perform<T>(T value)
    {
        Console.WriteLine("Called = " + value);
    }

    public static Delegate CreateAction(Type type)
    {
        var methodInfo = typeof (Program).GetMethod("Perform").MakeGenericMethod(type);
        var actionT = typeof (Action<>).MakeGenericType(type);
        return Delegate.CreateDelegate(actionT, methodInfo);
    }

    static void Main(string[] args)
    {
        CreateAction(typeof (int)).DynamicInvoke(5);
        Console.ReadLine();
    }
}

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