using System;

public class Program

{

    public static void Main()

    {

        var f = (IFoo) new Foo();

        Func(f);

        Console.WriteLine(f.Foo2);

    }

    static void Func(IFoo f)

    {

    f.Foo2 = 42;

    }

}

​

interface IFoo 

{

int Foo2 {get; set;}

}

    struct Foo : IFoo

    {

    public int Foo2 {get; set;}

    }