C# 操作符重载 模拟String

模拟String，让引用类型的使用像值类型一样

    class MyString
    {
        private static Dictionary<string, MyString> dic = new Dictionary<string, MyString>();
        string s;
        public MyString(string s)
        {
            this.s = s;
            dic[s] = this;
        }

        public static implicit operator MyString(string value)
        {
            if (dic.ContainsKey(value))
            {
                return dic[value];
            }
            return new MyString(value);
        }


        public static bool operator ==(MyString s1, MyString s2)
        {
            return s1.ToString() == s2.ToString();
        }
        public static bool operator !=(MyString s1, MyString s2)
        {
            return !(s1.ToString() == s2.ToString());
        }


        public override string ToString()
        {
            return s;
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            MyString ms1 = "1111";
            MyString ms2 = "1111";
            Test(ms1, ms2);

            ms2 = ms1;
            ms1 = ms1 + "changed";
            Test(ms1, ms2);

            Test(ms1, ms2);

            string s1 = "test";
            string s2 = "test";
            Test(s1, s2);

            s2 = s1;
            s1 = s1 + "change";
            Test(s1, s2);
        }
        static void Test(object obj1, object obj2)
        {
            Console.WriteLine("ob1:{0}  obj1:{1} ", obj1, obj2);
            Console.WriteLine("ob1==obj1: " + (obj1 == obj2).ToString());
            Console.WriteLine("引用相等:" + Object.ReferenceEquals(obj1, obj2).ToString());
            Console.WriteLine("-----------------");
        }
    }