Observer Design Pattern

/*
    When you are interested in state of an object and want to get notified when there is a change.
    The object being watched is called observable (subject) and whatever watches it, called observer.
*/

#include <iostream>
#include <vector>

// Observer interface
class Observer {
public:
	virtual void update(float temperature, float humidity, float pressure) = 0;
};

// Subject (WeatherStation) class
class WeatherStation {
private:
	float temperature;
	float humidity;
	float pressure;
	std::vector<Observer*> observers;

public:
	void registerObserver(Observer* observer) {
		observers.push_back(observer);
	}

	void removeObserver(Observer* observer) {
		// You can implement the removal logic if needed.
	}

	void notifyObservers() {
		for (Observer* observer : observers) {
			observer->update(temperature, humidity, pressure);
		}
	}

	void setMeasurements(float temp, float hum, float press) {
		temperature = temp;
		humidity = hum;
		pressure = press;
		notifyObservers();
	}
};

// Concrete Observer
class Display : public Observer {
public:
	void update(float temperature, float humidity, float pressure) {
		std::cout << "Display: Temperature = " << temperature
				<< "°C, Humidity = " << humidity
				<< "%, Pressure = " << pressure << " hPa"
				<< std::endl;
	}
};

int main() {
	WeatherStation weatherStation;

	// Create displays
	Display display1;
	Display display2;

	// Register displays as observers
	weatherStation.registerObserver(&display1);
	weatherStation.registerObserver(&display2);

	// Simulate weather data updates
	weatherStation.setMeasurements(25.5, 60, 1013.2);
	weatherStation.setMeasurements(24.8, 58, 1014.5);

	return 0;
}