Func<TResult>和Func<TSource, TResult>

TSource和TResult

/*Func<TResult>和Func<TSource, TResult>*/

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace ConAppTRusult{    class Program    {        static void Main(string[] args)        {            var obj = new User();            obj.TestTResult();        }    }    class User    {        public int ID { get; set; }        public string Name { get; set; }        public char Sex { get; set; }        public int Age { get; set; }        public List<User> GetUser()        {                       var list = new List<User>();            var u1 = new User();            u1.ID = 1;            u1.Name = "Alan";            u1.Sex = 'M';            u1.Age = 33;            list.Add(u1);            var u2 = new User();            u2.ID = 2;            u2.Name = "Betty";            u2.Sex = 'F';            u2.Age = 31;            list.Add(u2);            var u3 = new User();            u3.ID = 3;            u3.Name = "Cora";            u3.Sex = 'F';            u3.Age = 27;            list.Add(u3);            return list;        }        public static List<User> GetUserList()        {            return new List<User>();            //return new User().GetUser();        }        public static List<User> GetUserListByModel(User model)        {            return new List<User>();            //return new User().GetUser();        }        public static TResult GetModelList<TResult>(Func<TResult> GetFunc)        {            return default(TResult);        }        public static TResult GetModelList<TSource, TResult>(Func<TSource, TResult> GetFunc)        {            return default(TResult);        }        public static TResult GetModelList2<TResult>(Func<TResult> GetFunc) where TResult : class   //where TResult : List<User>        {            //return default(TResult);            return new User().GetUser() as TResult;        }        public static TResult GetModelList2<TSource, TResult>(Func<TSource, TResult> GetFunc) where TResult : List<User>        {            //return default(TResult);            return new User().GetUser() as TResult;        }        public void TestTResult()        {            GetModelList(GetUserList);            //GetModelList(GetUserListByModel);            GetModelList((User User) => GetUserListByModel(User));            //var list = new User().GetUser();            //var list = GetUserList();            //var list = GetModelList(GetUserList);     //error: list is null            var list = GetModelList2(GetUserList);      //right: list is not null                            //var list = GetModelList2((User User) => GetUserListByModel(User));//right: list is not null               foreach (var item in list)            {                              Console.WriteLine(item.ID + "-" + item.Name+"-"+item.Sex+"-"+item.Age);            }            //下面语句等价            //GetModelList2(GetUserList) <=> GetModelList2<List<User>>(GetUserList);        }    }}

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