Cannot convert type via a reference conversion, boxing conversion, unboxing conversion, wrapping conversion, or null type conversion

Question

In C#, if I have a parameter for a function where the parameter type is of an interface, how do a pass in an object that implements the interface.

Here is an example

Answer 1

In additional to List.Cast, C#'s generics provide a good support for Covariance and contravariance. This example causes it to work in the way I think you originally intended.

public class Program
{
    public static void Main()
    {
         Foo(new List());
    }

    public static void Foo(List bar) where T : IFim
    {
        throw new NotImplementedException();
    }

    public class IFim{}
    public class Fim : IFim{}
}