using System;

using System.Collections.Generic;

​

namespace Example

{

    public class BaseParamClass

    {

    }

    public class ListHandler 

    {

        private List<IBase<BaseParamClass>> list;

        public ListHandler()

        {

            list = new List<IBase<BaseParamClass>>();

        }

        public void Register(IBase<BaseParamClass> param)

        {

            list.Add(param);

        }

    }

    public interface IBase<T> where T : BaseParamClass

    {

        T Param {get; }

    }

    public class BaseClass : IBase<BaseParamClass>

    {

        private ListHandler listHandler;

        public BaseParamClass Param { get; private set; }

        public BaseClass(ListHandler listHandler)

        {

            this.listHandler = listHandler;

            listHandler.Register(this); //throws error

        }

    }

}