using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public interface IEntity

    {

        int Id { get; set; }

    }

    /* Code generated by the entity framework */

    public class YourEntities

    {

        public DbSet<User> Users { get; set; }  

        public DbSet<Book> Books { get; set; }  

        public DbSet<TEntity> Set<TEntity>() where TEntity : class

        {

            // Entity framework method  

        }

    }

    public class User : IEntity

    {

        public int Id { get; set; }

        public string Firstname { get; set; }

        public string Lastname { get; set; }

    }

    public class Book : IEntity

    {

        public int Id { get; set; }

        public string Name { get; set; }    

    }

    /* End of the code generated by the entity framework */

    public class BaseRepository<T> where T : IEntity

    {

        public YourEntities Entities { get; set; }

        public BaseRepository(YourEntities entities)

        {

            this.Entities = entities;

        }

        public List<T> GetAll()

        {

            // Return all element of the table containing T objects

            return this.Entities.Set<T>().ToList();

        }

    }

    public class UserRepository : BaseRepository<User>

    {

        public UserRepository(YourEntities entities)

            : base(entities)

        {

        }

        public List<User> GetAllUserSortByName()

        {

            return this.GetAll().OrderBy(u => u.Lastname).ThenBy(u => u.Firstname).ToList();

        }

    }

    public static void Main()

    {

        YourEntities entities = new YourEntities();

        UserRepository repo = new UserRepository(entities);

        List<User> users = repo.GetAllUserSortByName();

    }

}