#include <iostream>
 
    struct TimerService
    {
        virtual void handleTimerEvent() = 0;
 
        TimerService()
        {
        }
 
        void trigger()
        {
            handleTimerEvent();
        }
    };
 
    class A : public TimerService
    {
 
        const char* m_name;
 
    public:
        A(const char* name_) : TimerService(), m_name(name_) {}
 
        void handleTimerEvent() override
        {
            std::cout << "Handling timer event in " << m_name << '\n';
        }
    };
 
    void triggerEvent(TimerService& service)
    {
        service.trigger();
    }
 
    int main()
    {
        A a("A instance 'a'"), b("A instance 'b'");
        triggerEvent(b);
        triggerEvent(a);
    }

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