static void Main(string[] args)
{
Console.WriteLine("Starting Observer demo:");
WeatherData weatherData = new WeatherData();
CurrentConditionsDisplay display1 = new CurrentConditionsDisplay(weatherData);
weatherData.RegisterObserver(display1);
weatherData.SetMeasurements(20.3f, 50, 12);
weatherData.SetMeasurements(23.1f, 55, 17);
}
static void Main(string[] args)
{
WeatherData weatherData = new WeatherData();
CurrentConditionDisplay currentConditionDisplay = new CurrentConditionDisplay(weatherData);
weatherData.SetMeasurement(80, 65, 30.4f);
weatherData.RegisterObserver(currentConditionDisplay);
weatherData.SetMeasurement(80, 65, 30.4f);
weatherData.Remove(currentConditionDisplay);
weatherData.SetMeasurement(80, 65, 30.4f);
}
static void Main()
{
ISubject weatherData = new WeatherData();
IObserver conditionsDisplay = new ConditionsDisplay();
weatherData.RegisterObserver(conditionsDisplay);
weatherData.NotifyObservers(45, 10);
weatherData.NotifyObservers(35, 25);
Console.ReadLine();
}
public StatisticsDisplay(WeatherData weatherData)
{
this._weatherData = weatherData;
weatherData.RegisterObserver(this);
}
public ForecastDisplay(WeatherData weatherData)
{
this._weatherData = weatherData;
weatherData.RegisterObserver(this);
}
private void Start()
{
_weatherData.RegisterObserver(_currentConditionsDisplay);
_weatherData.RegisterObserver(_statisticsDisplay);
StartCoroutine(_MeasurementsChangeCoroutine());
}
static void Main(string[] args)
{
/*
* The Observer Pattern
*
* Example:
* A publisher creates a new magazine and begins publishing issues.
* You subscribve and receive issues as along as you stay subscribed.
* You can unsubscribe at any time.
* Others can also subscribe.
* Other can also unsubscribe.
* If Publisher ceases business, you stop receiving issues.
*
* Allows:
* -Subjests and Observers are "loosely coupled"
* -Strive for loosely coupled designs between objects that interact. (Design Principle #4)
*
* Implementation (Push):
*
* We define 3 interfaces:
* -ISubject (implemented by publisher, stores the list of subscribers, notifies on updates)
* -IObserver (implemented by subscriber, update method)
* -IDisplayElement (implemented by subscriber, display method)
*
* We define main class WatherData:
* -WatherData that implements ISubject
* -Notifies observers(subscribers) though method Update()
* -This doesn't know anything about observers
* -Subject doesn't care it keeps doing its job
*
* We define subscriber classes:
* -Each implements interfaces IObserver and IDisplayElement just to display info
* -Each receives Subject(Publisher) in constructor, subscribes itself to it, and keeps it in private field
* -To become an observer it needs to implement IObserver
*
*/
//create concrete subject(publisher)
WeatherData weatherData = new WeatherData();
//create Observer(subscriber) and register with Subject(publisher)
CurrentConditionsDisplay currentConditions = new CurrentConditionsDisplay(weatherData); //subscribe in constructor of observer(subscriber), PUSH subscription
//create more Observers(subscribers)
weatherData.RegisterObserver(new StatisticsDisplay(weatherData)); //subscribe in method of subject(publisher), PULL subscription
ForecastDisplay forecastDisplay = new ForecastDisplay(weatherData);
//refresh data at Subject(publisher), simulate new data from sensors
weatherData.SetMeasurements(new Data()
{
Temp = 80,
Humidity = 65,
Pressure = 29.2
});
weatherData.SetMeasurements(new Data()
{
Temp = 82,
Humidity = 70,
Pressure = 30.4
});
weatherData.SetMeasurements(new Data()
{
Temp = 78,
Humidity = 90,
Pressure = 29.4
});
Console.ReadLine();
}
