using System;

using System.Collections.Generic;

using System.Linq;

​

public enum OddsCategory

{

    Fulltime,

    Firsthalf,

    Secondhalf

}

​

public interface IOdds

{

    int Id { get; }

}

​

public class FullTime : IOdds

{

    public int Id { get; set; }

    public string Book { get; set; }

    public decimal? Payout { get; set; }

}

​

public class Program

{

    public static void Main()

    {

        var program = new Program();

        List<FullTime> ft = program.GetOddsGeneric<FullTime>("...", OddsCategory.Fulltime).ToList();

        Console.WriteLine(ft);

    }

    public IEnumerable<IOdds> GetOdds(string link, OddsCategory category) {

        switch(category) {

            case OddsCategory.Fulltime: 

                {

                var list = new List<IOdds>();

                list.Add(new FullTime());

                return list;

                }

                break;

        }

        return new List<IOdds>();

    }

    public IEnumerable<T> GetOddsGeneric<T>(string link, OddsCategory category) where T: IOdds {

        var baseEnumerable = this.GetOdds(link, category);

        return baseEnumerable.Select((x) => (T)x);

    }

}