Refactor Driver–Bus Relationship

#include <iostream>
using namespace std;

/**
 * The Bus class represents the shared hardware resource.
 * It follows the RAII pattern: starts on construction, stops on destruction.
 */
class Bus {
public:
    Bus() {
        cout << "Bus ready" << endl;
    }

    ~Bus() {
        cout << "Bus stopped" << endl;
    }

    void write(int addr, int val) {
        cout << "Bus write: " << addr << " " << val << endl;
    }
};

/**
 * The Driver class uses the Bus.
 * Instead of inheriting, it holds a reference to a shared Bus object.
 */
class Driver {
private:
    Bus& sharedBus; // Reference to the single hardware bus

public:
    // Constructor takes a reference to the shared bus
    Driver(Bus& bus) : sharedBus(bus) {
        cout << "Driver started" << endl;
    }

    // Uses the shared bus to perform operations
    void operate(int addr, int val) {
        sharedBus.write(addr, val);
    }

    ~Driver() {
        cout << "Driver stopped" << endl;
    }
};

int main() {
    int a1, v1, a2, v2;
    if (!(cin >> a1 >> v1 >> a2 >> v2)) return 0;

    // 1. Create exactly ONE Bus object
    Bus hardwareBus;

    // 2. Use a scope to control the lifetime of the drivers
    {
        // 3. Create two drivers sharing the same bus reference
        Driver d1(hardwareBus);
        Driver d2(hardwareBus);

        // 4. Perform operations
        d1.operate(a1, v1);
        d2.operate(a2, v2);
        
        // Drivers go out of scope here, printing "Driver stopped"
    }

    // Bus goes out of scope here, printing "Bus stopped"
    return 0;
}