Board-Independent Status Indicator

#include <iostream>
using namespace std;

/*
Select exactly ONE hardware board at build time.
*/
// #define BOARD_TYPE_A
#define BOARD_TYPE_B

// Abstract interface used by application code
class StatusIndicator {
public:
    virtual void toggle() = 0;
    virtual bool isOn() const = 0;
    virtual ~StatusIndicator() = default;
};

/*
TASK FOR LEARNER:

- Create TWO board-specific implementations of StatusIndicator
- Select exactly one using conditional compilation
- Enforce compile-time errors for invalid selections
- Implement the factory function below

DO NOT modify main()
*/

// Factory function declaration (not implemented here)
class IndicatorA : public StatusIndicator{
    bool state = false;
    public:
        void toggle()override{
            state = !state;
        }
        bool isOn() const override{
            if(state){
                return true;
            }
            return false;
        }

};

class IndicatorB : public StatusIndicator{
    bool state = false;
    public:
        void toggle()override{
            state = !state;
        }
        bool isOn() const override{
            if(state){
                return true;
            }
            return false;
        }

};

StatusIndicator& getStatusIndicator(){
    static IndicatorA a;
    static IndicatorB b;

    #ifdef BOARD_TYPE_A
        return a;
    #elif defined(BOARD_TYPE_B)
        return b;
    #else
        #error "No valid board type defined"
    #endif
}

int main() {
    int n;
    cin >> n;

    StatusIndicator& indicator = getStatusIndicator();

    for (int i = 0; i < n; ++i) {
        int evt;
        cin >> evt;

        if (evt == 1) {
            indicator.toggle();
        }

        cout << (indicator.isOn() ? "STATUS=ON\n" : "STATUS=OFF\n");
    }

    return 0;
}