如何在C＃4.0中使用动态类型调用静态方法？

Question

In C#4.0, we have dynamic type, but how to invoke static method of dynamic type object?

Below code will generate exception at run time. The dynamic object is from C# class, but it could be object from other languages through DLR. The point is not how to invoke static method, but how to invoke static method of dynamic object which could not be created in C# code.

class Foo
{
    public static int Sum(int x, int y)
    {
        return x + y;
    }
}

class Program
{

    static void Main(string[] args)
    {
        dynamic d = new Foo();
        Console.WriteLine(d.Sum(1, 3));

    }
}

IMHO, dynamic is invented to bridge C# and other programming language. There is some other language (eg Java) allows to invoke static method through object instead of type.

BTW, The introduction of C#4.0 is not so impressive compared to C#3.0.

Answer 1

C＃4不直接支持此功能，但是此博客文章中有一个有趣的解决方法： http : //blogs.msdn.com/davidebb/archive/2009/10/23/using-c-dynamic-to-call-static- Members.aspx

Answer 2

While C# doesn't support it, the DLR does. You can programmatically access the dlr calls with Dynamitey

var staticContext = InvokeContext.CreateStatic ;

Console.WriteLine(Dynamic.InvokeMember(staticContext(typeof(Foo)), "Sum", 1,3));

Answer 3

One possible workaround would be to use reflection.

dynamic d = new Foo();

var sum = (int)d.GetType()
                .GetMethod("Sum")
                .Invoke(d, new object[] { 1, 3 });
Console.WriteLine(sum);