DesignPattern_Behavioral_Command

void Main()
{
    Invoker invoker = new Invoker();
    invoker.Add(new CommandA());
    invoker.Add(new CommandB());
    invoker.Notify();
}

class Receiver{
    public void ShowA(){}
    public void ShowB(){}
}
abstract class Command{
    protected Receiver receiver = new Receiver();
    public abstract void Show();
}
class CommandA:Command{
    public override void Show(){
        receiver.ShowA();
    }
}
class CommandB:Command{
    public override void Show(){
        receiver.ShowB();
    }
}
class Invoker{
    List<Command> commands = new List<Command>();
    public void Add(Command c){ commands.Add(c); }
    public void Remove(Command c){ commands.Remove(c); }
    public void Notify(){
        foreach (var command in commands)
        {
            command.Show();
        }
    }
}