Ch2Weather first version

Ch2Weather/Ch2Weather.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net9.0</TargetFramework>
+        <LangVersion>latestmajor</LangVersion>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+</Project>

Ch2Weather/Exercise1.mermaid

@@ -0,0 +1,38 @@
+classDiagram
+    class WeatherData {
+        getTemperature()
+        getHumidity()
+        getPressure()
+        measurementsChanged()
+
+        subscribe(observer: IWeatherObserver)
+        unsubscribe(observer: IWeatherObserver)
+        notify(data: WeatherRecord)
+    }
+    class WeatherRecord {
+        f32 temperature
+        f32 humidity
+        f32 pressure
+    }
+    class IWeatherObserver {
+        update(data: WeatherRecord)
+    }
+    class IWeatherSubject {
+        subscribe(observer: IWeatherObserver)
+        unsubscribe(observer: IWeatherObserver)
+        notify(data: WeatherRecord)
+    }
+    class WeatherScreen1 {
+        update(data: WeatherRecord)
+        draw()
+    }
+    IWeatherSubject <|.. WeatherData
+    IWeatherObserver <|.. WeatherScreen1
+    IWeatherObserver <-- IWeatherSubject : observers
+    WeatherData <-- WeatherScreen1 : Subjects
+    IWeatherObserver .. IWeatherSubject
+    class IDisplayElement {
+        draw()
+    }
+    IDisplayElement <|.. WeatherScreen1
+    

Ch2Weather/Program.cs

@@ -0,0 +1,10 @@
+// See https://aka.ms/new-console-template for more information
+
+using Ch2Weather;
+
+var weatherData = new WeatherData(new WeatherRecord(0, 0,0));
+_ = new CurrentConditionsDisplay(weatherData);
+_ = new HeatIndexDisplay(weatherData);
+weatherData.WeatherRecord = new WeatherRecord(25, 50, 30);
+weatherData.WeatherRecord = new WeatherRecord(35, 55, 29.8);
+weatherData.WeatherRecord = new WeatherRecord(45, 60, 29.6);

Ch2Weather/Weather.cs

@@ -0,0 +1,95 @@
+namespace Ch2Weather;
+
+public record struct WeatherRecord(double Temperature, double Humidity, double Pressure);
+
+public interface IWeatherSubject {
+    void Subscribe(IWeatherObserver o);
+    void Unsubscribe(IWeatherObserver o);
+    void NotifyObservers();
+}
+
+public interface IWeatherObserver {
+    void Update(WeatherRecord wr);
+}
+
+public interface IWeatherDisplay {
+    void Display();
+}
+
+public class WeatherData(WeatherRecord weatherRecord) : IWeatherSubject {
+    private readonly List<IWeatherObserver> _observers = [];
+    private WeatherRecord _weatherRecord = weatherRecord;
+
+    public WeatherRecord WeatherRecord {
+        get => _weatherRecord;
+        set {
+            _weatherRecord = value;
+            NotifyObservers();
+        }
+    }
+
+    public void Subscribe(IWeatherObserver o) {
+        _observers.Add(o);
+    }
+
+    public void Unsubscribe(IWeatherObserver o) {
+        _observers.Remove(o);
+    }
+
+    public void NotifyObservers() {
+        foreach (var o in _observers) {
+            o.Update(_weatherRecord);
+        }
+    }
+}
+
+public class CurrentConditionsDisplay : IWeatherObserver, IWeatherDisplay {
+    private IWeatherSubject _subject;
+    private double _temperature = 0;
+    private double _humidity = 0;
+    
+    public CurrentConditionsDisplay(IWeatherSubject subject) {
+        _subject = subject;
+        subject.Subscribe(this);
+    }
+
+    public void Update(WeatherRecord wr) {
+        _temperature = wr.Temperature;
+        _humidity = wr.Humidity;
+        Display();
+    }
+
+    public void Display() {
+        Console.WriteLine($"Current conditions: {_temperature}C degrees and {_humidity}% humidity.");
+    }
+}
+
+public class HeatIndexDisplay : IWeatherObserver, IWeatherDisplay {
+    private IWeatherSubject _subject;
+    private WeatherRecord _weatherRecord = new WeatherRecord(0,0,0);
+
+    public HeatIndexDisplay(IWeatherSubject subject) {
+        _subject = subject;
+        subject.Subscribe(this);
+    }
+    
+    private double ComputeHeatIndex(double t, double rh) {
+        return (16.923 + (0.185212 * t) + (5.37941 * rh) - (0.100254 * t * rh) +
+                (0.00941695 * (t * t)) + (0.00728898 * (rh * rh)) +
+                (0.000345372 * (t * t * rh)) - (0.000814971 * (t * rh * rh)) +
+                (0.0000102102 * (t * t * rh * rh)) - (0.000038646 * (t * t * t)) + (0.0000291583 *
+                    (rh * rh * rh)) + (0.00000142721 * (t * t * t * rh)) +
+                (0.000000197483 * (t * rh * rh * rh)) - (0.0000000218429 * (t * t * t * rh * rh)) +
+                0.000000000843296 * (t * t * rh * rh * rh)) -
+               (0.0000000000481975 * (t * t * t * rh * rh * rh));
+    }  
+    public void Update(WeatherRecord wr) {
+        _weatherRecord = wr;
+        Display();
+    }
+
+    public void Display() {
+        var heatIndex = ComputeHeatIndex(_weatherRecord.Temperature, _weatherRecord.Humidity);
+        Console.WriteLine($"Heat Index is {heatIndex}");
+    }
+}

HeadFirstDesignPatterns.sln

@@ -2,6 +2,8 @@
 Microsoft Visual Studio Solution File, Format Version 12.00
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Ch1Duck", "Ch1Duck\Ch1Duck.csproj", "{941002B3-4C8C-4A9A-9071-7FD27E9E5C9F}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Ch2Weather", "Ch2Weather\Ch2Weather.csproj", "{D457D364-C0AB-42D2-A0B7-245D038CE8D1}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -12,5 +14,9 @@ Global
 		{941002B3-4C8C-4A9A-9071-7FD27E9E5C9F}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{941002B3-4C8C-4A9A-9071-7FD27E9E5C9F}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{941002B3-4C8C-4A9A-9071-7FD27E9E5C9F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{D457D364-C0AB-42D2-A0B7-245D038CE8D1}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{D457D364-C0AB-42D2-A0B7-245D038CE8D1}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{D457D364-C0AB-42D2-A0B7-245D038CE8D1}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{D457D364-C0AB-42D2-A0B7-245D038CE8D1}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 EndGlobal