Allow access to but prevent instantiation of a nested class by external classes

Question

I\'m looking to define a nested class that is accessible to the container class and external classes, but I want to control instantiation of the nested class, such that only

Answer 1

It is impossible to declare class in such way. I think that the best way for you would be to declare class as private and expose it through public interface:

class Program
{
    static void Main(string[] args)
    {
       // new S.N(); does not work
        var n = new S().Create();
    }
}

class S
{
    public interface IN
    {
        int MyProperty { get; set; }
    }
    class N : IN
    {
        public int MyProperty { get; set; }
        public N()
        {

        }
    }

    public IN Create()
    {
        return new N();
    }
}