using System;

public class Consumer
{
    private string name, interestedIn;

    public Consumer(string name, string interestedIn)
    {
        this.name = name;
        this.interestedIn = interestedIn;
    }

    public void NewCarIsHere(object sender, CarInfoEventArgs e)
    {
        if (e.Car.Contains(interestedIn))
            Console.WriteLine("info dla {0}; jest nowe auto: {1} dostępne od {2} do {3}",
                name, e.Car, e.BeginTime.ToShortDateString(), e.EndTime.ToShortDateString());
    }
}




using System;

public class CarInfoEventArgs : EventArgs
{
    public CarInfoEventArgs(string car, DateTime beginTime, DateTime endTime)
    {
        this.Car = car;
        BeginTime = beginTime;
        EndTime = endTime;
    }

    public string Car { get; private set; }

    public DateTime BeginTime { get; private set; }

    public DateTime EndTime { get; private set; }
}

public class CarDealer
{
    public event EventHandler<CarInfoEventArgs> NewCarInfo;

    public void NewCar(string car, DateTime beginTime, DateTime endTime)
    {
        Console.WriteLine("Dealer, nowe auto: {0}, dostępne od {1} do {2}",
            car, beginTime.ToShortDateString(), endTime.ToShortDateString());
        NewCarInfo?.Invoke(this, new CarInfoEventArgs(car, beginTime, endTime));
    }
}