在运行时创建委托类型 [英] Create delegate type in runtime

问题描述

我尝试使用Expression类创建委托类型，但是当我尝试从MethodInfo实例创建委托时，出现ArgumentException.我使用.NET 4.0此处代码:

I try create delegate type using an Expression class, but when I try create delegate from instance of MethodInfo I've got an ArgumentException. I using .NET 4.0 Here code:

        var method = /*...*/;
        List<Type> tArgs = new List<Type> { method.ReturnType };
        var mparams = method.GetParameters();
        mparams.ToList().ForEach(p => tArgs.Add(p.ParameterType));
        var delDecltype = Expression.GetDelegateType(tArgs.ToArray());
        return Delegate.CreateDelegate(delDecltype, method);

P.S.对不起，我的英语不好；)

P.S. Sorry for my bad english;)

推荐答案

如果您阅读这意味着此代码应该有效:

That means this code should work:

var tArgs = new List<Type>();
foreach (var param in method.GetParameters())
    tArgs.Add(param.ParameterType);
tArgs.Add(method.ReturnType);
var delDecltype = Expression.GetDelegateType(tArgs.ToArray());
return Delegate.CreateDelegate(delDecltype, method);

该代码仅适用于静态方法.如果要从实例方法创建委托，则需要提供要在其上调用该方法的实例.为此，将最后一行更改为:

This code works for static methods only though. If you want create a delegate from instance method, you need to provide the instance you want to call the method on. To do that, change the last line to:

return Delegate.CreateDelegate(delDecltype, instance, method);

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