C# 自定义事件

 public class CarInfoEventArgs : EventArgs
    {
        public string Car { get; set; }
        public CarInfoEventArgs(string car)
        {
            this.Car = car;
        }
    }
    
    public class CarDealer
    {
        public event EventHandler<CarInfoEventArgs> NewCarInfo;
        
        public void NewCar(string car)
        {
            Console.WriteLine("CarDealer,new car {0}", car);
            RaiseNewCarInfo(car);
        }
        protected virtual void RaiseNewCarInfo(string car)
        {
            EventHandler<CarInfoEventArgs> newCarInfo = NewCarInfo;
            if (newCarInfo != null)
                newCarInfo(this, new CarInfoEventArgs(car));
        }
    }

 public class Consumer
    {
       private string name;
       public Consumer(string name)
       {
           this.name = name;
       }
       public void NewCarIsHere(object sender,CarInfoEventArgs e)
       {
           Console.WriteLine("{0}: car {1} is new", name, e.Car);
       }
    }

 var dealer = new CarDealer();

            var michael = new Consumer("Michael");
            dealer.NewCarInfo += michael.NewCarIsHere;

            dealer.NewCar("Ferrari");

            var nick = new Consumer("Sebastian");
            dealer.NewCarInfo += nick.NewCarIsHere;

            dealer.NewCar("Mercedes");

            dealer.NewCarInfo -= michael.NewCarIsHere;

            dealer.NewCar("Red Bull Racing");