public void Buy(string productName, PaySystem paySystem, PostSystem postSystem)
{
Thread payment = new Thread(paySystem.Pay);
Thread parcelSending = new Thread(postSystem.SendParcel);
payment.Start();
payment.Join();
parcelSending.Start();
parcelSending.Join();
Console.WriteLine("{0} was bought", productName);
}
public void Buy(Shop shop, string productName, PaySystem paySystem, PostSystem postSystem)
{
Thread buyThread = new Thread(() => shop.Buy(productName, paySystem, postSystem));
buyThread.Start();
}