static void Main()
{
TrainSignal trainSignal = new TrainSignal();
new Car(trainSignal);
new Car(trainSignal);
new Car(trainSignal);
trainSignal.HereComesATrain();
// Event is a delegate reference with two restrictions on it:
// 1. You cannot invoke the delegate reference directly
// 2. You cannot assign to it directly
// Thus, this code cannot compile:
// trainSignal.TrainIsComing();
// trainSignal.TrainIsComing = null;
// Thus, this code can compile:
trainSignal.TrainIsComing += null;
}
public Car(TrainSignal trainSignal)
{
// We are observing the trainSignal
// When something happens, the trainSignal notifies us via the StopTheCar method
trainSignal.TrainIsComing += StopTheCar;
}