learning-hour-maker/exercises/slice-with-lambda/solution/SliceWithLambda/WeatherStationSolution.cs

// Example 2 solution — Weather Station domain demo of Slice with Lambda (C#), after
//
// Lambda extracted (step 1), slid to the top (step 2), method extracted
// below the guard (step 3). The constructor now takes the lambda directly,
// so tests construct with new SprinklerController(() => 200).
//
// Condensed mechanics: https://sammancoaching.org/refactorings/slice.html
// (where that page says mock, we use a lambda instead).

using System;

public enum SunExposure
{
    Shady,
    Sunny
}

public enum WateringDuration
{
    None,
    Medium,
    Short
}

public class LightSensor
{
    private readonly Random _rng = new Random();    // stand-in for hardware noise

    public byte Read()
    {
        return (byte)_rng.Next(256);
    }
}

public class SprinklerController
{
    private readonly Func<byte> _readLight;         // the sensor, as a lambda
    private bool _wateredToday;                     // event-style client state

    public SprinklerController(Func<byte> readLight)
    {
        _readLight = readLight;
    }

    public WateringDuration ScheduleWatering()
    {
        Func<byte> readLight = () => _readLight();  // lambda definition at the top
        return ScheduleWateringTail(readLight);     // pass the lambda on
    }

    private WateringDuration ScheduleWateringTail(Func<byte> readLight)
    {
        if (_wateredToday)                          // guard: client state, stays
        {
            return WateringDuration.None;
        }

        _wateredToday = true;                       // set only after watering
        byte reading = readLight();                 // middle: the stubbed lambda
        SunExposure exposure = ToSunExposure(reading);
        if (exposure == SunExposure.Sunny)          // tail: complex behaviour below
        {                                           // the extraction point
            return WateringDuration.Medium;
        }
        return WateringDuration.Short;
    }

    private static SunExposure ToSunExposure(byte reading)
    {
        return reading > 128 ? SunExposure.Sunny : SunExposure.Shady;
    }
}