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  1. PO
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    <p>A more pattern oriented solution (but without function pointers) could be the following. You could parametrize the WeatherObserver-Class to get only the values, you want. </p> <pre><code>#include &lt;list&gt; #include &lt;iostream&gt; class Observable; //forward declaration //Base class for all observers class Observer { friend class Observable; //allow access to observedSubject protected: Observable *observedSubject; public: virtual void update(){}; }; //Base class for all observables class Observable { private: std::list&lt;Observer * const&gt; m_registeredObservers; public: ~Observable() { //delete the observers std::list&lt;Observer * const&gt;::iterator it = m_registeredObservers.begin(); while (it != m_registeredObservers.end()) { delete *it; it = m_registeredObservers.erase(it); } } void addObserver(Observer * const _pObserver) { _pObserver-&gt;observedSubject = this; m_registeredObservers.push_back(_pObserver); } void removeObserver(Observer * const _pObserver) { m_registeredObservers.remove(_pObserver); delete _pObserver; } void notifyObservers() { std::list&lt;Observer * const&gt;::iterator it = m_registeredObservers.begin(); while (it != m_registeredObservers.end()) { (*it)-&gt;update(); it++; } } }; //Concrete Observable class WeatherData : public Observable { private: float temperature; float humidity; float pressure; public: WeatherData(): temperature(0), humidity(0), pressure(0) {}; float getTemperature () const { return temperature; } float getHumidity () const { return humidity; } float getPressure () const { return pressure; } void setTemperature(float _temperature) { if (temperature != _temperature) { temperature = _temperature; notifyObservers(); } } void setHumidity(float _humidity) { if (humidity != _humidity) { humidity = _humidity; notifyObservers(); } } void setPressure(float _pressure) { if (pressure != _pressure) { pressure = _pressure; notifyObservers(); } } }; //Concrete implementation of an weather observer class WeatherObserver : public Observer { public: WeatherObserver():Observer(){}; void update() { WeatherData* pWeatherPtr = static_cast&lt;WeatherData*&gt;(observedSubject); if (pWeatherPtr != 0) { float actHumidity = pWeatherPtr-&gt;getHumidity(); float actPressure = pWeatherPtr-&gt;getPressure(); float actTemperature = pWeatherPtr-&gt;getTemperature(); //do something with the data std::cout &lt;&lt; "WeatherObserver update" &lt;&lt; std::endl; std::cout &lt;&lt; "Temperature : " &lt;&lt; actTemperature &lt;&lt; std::endl; std::cout &lt;&lt; "Humidity : " &lt;&lt; actHumidity &lt;&lt; std::endl; std::cout &lt;&lt; "Pressure : " &lt;&lt; actPressure &lt;&lt; std::endl; } } }; int main() { WeatherData weatherData; Observer * pObserver = new WeatherObserver(); weatherData.addObserver(pObserver); weatherData.setHumidity(100); weatherData.setTemperature(100); } </code></pre>
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    1. POImplementing Observer pattern when observers wish to observe different items
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    1. USAquilaRapax
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    1. COthat is indeed a very decent solution, but I'll take some time to digest it. Thanks much.
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      1. USAquarius_Girl
    2. CODidn't the question effectively call for it to be possible to filter observer notifications for different aspects of the weather data that change?
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      1. USPete
 

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