using System;

using System.Reflection;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var genericTypes = Assembly.GetExecutingAssembly().GetTypes().Where(i => i.IsGenericType);

        foreach(var item in genericTypes)

        {

            Console.WriteLine(item);

​

            // -- Notice when using reflection this generic is "open". This means the generic type is not defined.

            Console.WriteLine(item.IsGenericTypeDefinition);

            // -- If you get the generic type with the parameter defined it is no longer "open".

            var closed = typeof(Generic<ISpecial>);

            Console.WriteLine(closed.IsGenericTypeDefinition);

            // -- To close a generic type there is a method.

            item.MakeGenericType(typeof(ISpecial));

            Console.WriteLine(item.IsGenericTypeDefinition);

            // -- The "open" "closed" matters because you can only create an instance of a "closed" type.

            // -- This is also true for methods. You can only invoke methods on "closed" types. ie IsGenericMethodDefinition.

        }

        // -- You can get all information for generics that is useful when using reflection.

        // -- For instance, getting the type constraints.

        foreach(var item in typeof(ConstrainedGeneric<>).GetGenericArguments())

        {

            foreach(var p in item.GetGenericParameterConstraints())

            {

                Console.WriteLine(p);

            }

        }

    }

    public interface ISpecial

    {

    }

​

    public class Generic<T>

    {

        public T DoSomething()

        {

            return default(T);

        }

    }

    public class ConstrainedGeneric<T> where T: ISpecial

    {

        public T DoSomething()

        {

            return default(T);

        }

    }

    public class NotGeneric

    {

    }

}