How to invoke static method in C#4.0 with dynamic type?

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 (e.g. 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.

Syst

Answer 1

This is not supported directly by C# 4 but there's an interesting workaround in this blog post: http://blogs.msdn.com/davidebb/archive/2009/10/23/using-c-dynamic-to-call-static-members.aspx

Annamaeannamaria

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));

Acima

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);

Matthaus