敏捷软件开发：原则、模式与实践——第20章　咖啡的启示

namespace CoffeeMaker
{
    public enum WarmerPlateStatus
    {
        WARMER_EMPTY,
        POT_EMPTY,
        POT_NOT_EMPTY
    };
    public enum BoilerStatus
    {
        EMPTY, NOT_EMPTY
    };
    public enum BrewButtonStatus
    {
        PUSHED, NOT_PUSHED
    };
    public enum BoilerState
    {
        ON, OFF
    };
    public enum WarmerState
    {
        ON, OFF
    };
    public enum IndicatorState
    {
        ON, OFF
    };
    public enum ReliefValveState
    {
        OPEN, CLOSED
    };
    public interface CoffeeMakerAPI
    {
        /*
        * This function returns the status of the warmer-plate
        * sensor. This sensor detects the presence of the pot
        * and whether it has coffee in it.
        */
        WarmerPlateStatus GetWarmerPlateStatus();
        /*
        * This function returns the status of the boiler switch.
        * The boiler switch is a float switch that detects if
        * there is more than 1/2 cup of water in the boiler.
        */
        BoilerStatus GetBoilerStatus();
        /*
        * This function returns the status of the brew button.
        * The brew button is a momentary switch that remembers
        * its state. Each call to this function returns the
        * remembered state and then resets that state to
        * NOT_PUSHED.
        *
        * Thus, even if this function is polled at a very slow
        * rate, it will still detect when the brew button is
        * pushed.
        */
        BrewButtonStatus GetBrewButtonStatus();
        /*
        * This function turns the heating element in the boiler
        * on or off.
        */
        void SetBoilerState(BoilerState s);
        /*
        * This function turns the heating element in the warmer
        * plate on or off.
        */
        void SetWarmerState(WarmerState s);
        /*
        * This function turns the indicator light on or off.
        * The indicator light should be turned on at the end
        * of the brewing cycle. It should be turned off when
        * the user presses the brew button.
        */
        void SetIndicatorState(IndicatorState s);
        /*
        * This function opens and closes the pressure-relief
        * valve. When this valve is closed, steam pressure in
        * the boiler will force hot water to spray out over
        * the coffee filter. When the valve is open, the steam
        * in the boiler escapes into the environment, and the
        * water in the boiler will not spray out over the filter.
        */
        void SetReliefValveState(ReliefValveState s);
    }
}

        public class Light
        {
            public void On()
            {
                CoffeeMaker.api.SetIndicatorState(IndicatorState.ON);
            }
            public void Off()
            {
                CoffeeMaker.api.SetIndicatorState(IndicatorState.OFF);
            }
        }

    public interface Heater
    {
        void TurnOn();
        void TurnOff();
    }

    public class M4UserInterface : UserInterface
    {
        private void CheckButton()
        {
            BrewButtonStatus status =
            CoffeeMaker.api.GetBrewButtonStatus();
            if (status == BrewButtonStatus.PUSHED)
            {
                StartBrewing();
            }
        }
    }

    public class UserInterface
    {
        private HotWaterSource hws;
        private ContainmentVessel cv;
        public void Done() { }
        public void Complete() { }
        protected void StartBrewing()
        {
            if (hws.IsReady() && cv.IsReady())
            {
                hws.Start();
                cv.Start();
            }
        }
    }

    public class M4HotWaterSource : HotWaterSource
    {
        public override bool IsReady()
        {
            BoilerStatus status =
            CoffeeMaker.api.GetBoilerStatus();
            return status == BoilerStatus.NOT_EMPTY;
        }
    }

    public class M4ContainmentVessel : ContainmentVessel
    {
        public override bool IsReady()
        {
            WarmerPlateStatus status =
            CoffeeMaker.api.GetWarmerPlateStatus();
            return status == WarmerPlateStatus.POT_EMPTY;
        }
    }

    public class M4HotWaterSource : HotWaterSource
    {
        private CoffeeMakerAPI api;
        public M4HotWaterSource(CoffeeMakerAPI api)
        {
            this.api = api;
        }
        public override bool IsReady()
        {
            BoilerStatus status = api.GetBoilerStatus();
            return status == BoilerStatus.NOT_EMPTY;
        }
        public override void Start()
        {
            api.SetReliefValveState(ReliefValveState.CLOSED);
            api.SetBoilerState(BoilerState.ON);
        }
    }

    public class M4ContainmentVessel : ContainmentVessel
    {
        private CoffeeMakerAPI api;
        private bool isBrewing = false;
        public M4ContainmentVessel(CoffeeMakerAPI api)
        {
            this.api = api;
        }
        public override bool IsReady()
        {
            WarmerPlateStatus status = api.GetWarmerPlateStatus();
            return status == WarmerPlateStatus.POT_EMPTY;
        }
        public override void Start()
        {
            isBrewing = true;
        }
    }

public interface Pollable
{
    void Poll();
}

        public static void Main(string[] args)
        {
            CoffeeMakerAPI api = new M4CoffeeMakerAPI();
            M4UserInterface ui = new M4UserInterface(api);
            M4HotWaterSource hws = new M4HotWaterSource(api);
            M4ContainmentVessel cv = new M4ContainmentVessel(api);
            ui.Init(hws, cv);
            hws.Init(ui, cv);
            cv.Init(hws, ui);
            while (true)
            {
                ui.Poll();
                hws.Poll();
                cv.Poll();
            }
        }

    public class M4UserInterface : UserInterface,Pollable
    {
        private CoffeeMakerAPI api;
        public M4UserInterface(CoffeeMakerAPI api)
        {
            this.api = api;
        }
        public void Poll()
        {
            BrewButtonStatus status = api.GetBrewButtonStatus();
            if (status == BrewButtonStatus.PUSHED)
            {
                StartBrewing();
            }
        }
    }