C++ Event Mechanism Implementation Guide

Implementing event mechanisms in C++ typically requires the use of callback functions or the observer pattern. Here is a simple implementation method:

1. Callback function: Define an event class that includes a pointer to a callback function. When the event occurs, call the callback function to handle the event. Example code is as follows:

#include <iostream>
#include <functional>

class Event {
public:
    using Callback = std::function<void()>;

    Event(Callback callback) : m_callback(callback) {}

    void trigger() {
        if (m_callback) {
            m_callback();
        }
    }

private:
    Callback m_callback;
};

void handleEvent() {
    std::cout << "Event handled" << std::endl;
}

int main() {
    Event event(handleEvent);
    event.trigger();

    return 0;
}

1. Observer pattern: defines a subject class and an observer class, the subject class contains methods to register observers and notify observers. Sample code is as follows:

#include <iostream>
#include <vector>

class Observer {
public:
    virtual void update() = 0;
};

class Subject {
public:
    void addObserver(Observer* observer) {
        m_observers.push_back(observer);
    }

    void notifyObservers() {
        for (Observer* observer : m_observers) {
            observer->update();
        }
    }

private:
    std::vector<Observer*> m_observers;
};

class EventObserver : public Observer {
public:
    void update() override {
        std::cout << "Event handled" << std::endl;
    }
};

int main() {
    Subject subject;
    EventObserver eventObserver;

    subject.addObserver(&eventObserver);
    subject.notifyObservers();

    return 0;
}

The above are two simple methods to implement event mechanisms, developers can choose the appropriate method based on their specific requirements during actual development.