如何使用给定的 Type 对象调用泛型方法? [英] How to call generic method with a given Type object?

问题描述

我想用给定的类型对象调用我的泛型方法.

I want to call my generic method with a given type object.

void Foo(Type t)
{
     MyGenericMethod<t>();
}

显然不起作用.

我怎样才能让它发挥作用?

How can I make it work?

推荐答案

您的代码示例将不起作用，因为泛型方法需要类型标识符，而不是 Type 类的实例.你必须使用反射来做到这一点:

Your code sample won't work, because the generic method expects a type identifier, not a an instance of the Type class. You'll have to use reflection to do it:

public class Example {

    public void CallingTest()
    {
        MethodInfo method = typeof (Example).GetMethod("Test");
        MethodInfo genericMethod = method.MakeGenericMethod(typeof (string));
        genericMethod.Invoke(this, null);

    }

    public void Test<T>()
    {
        Console.WriteLine(typeof (T).Name);
    }
}

请记住，这非常脆弱，我宁愿建议您寻找另一种模式来调用您的方法.

Do keep in mind that this is very brittle, I'd rather suggest finding another pattern to call your method.

另一种hacky解决方案(也许有人可以让它更简洁一些)是使用一些表达魔法:

Another hacky solution (maybe someone can make it a bit cleaner) would be to use some expression magic:

public class Example {

    public void CallingTest()
    {
        MethodInfo method = GetMethod<Example>(x => x.Test<object>());
        MethodInfo genericMethod = method.MakeGenericMethod(typeof (string));
        genericMethod.Invoke(this, null);

    }

    public static MethodInfo GetMethod<T>(Expression<Action<T>> expr)
    {
        return ((MethodCallExpression) expr.Body)
            .Method
            .GetGenericMethodDefinition();
    }

    public void Test<T>()
    {
        Console.WriteLine(typeof (T).Name);
    }
}

注意在 lambda 中将对象"类型标识符作为泛型类型参数传递.无法这么快地想出如何解决这个问题.无论哪种方式，我认为这是编译时安全的.不知何故感觉不对:/

Note passing the 'object' type identifier as a generic type argument in the lambda. Couldn't figure out so quickly how to get around that. Either way, this is compile-time safe I think. It just feels wrong somehow :/

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