观察者模式
#include <iostream>
#include <vector>
// 定义主题接口
class Subject {
public:
virtual ~Subject() {}
// 注册/移除观察者
virtual void registerObserver(void(*callback)(const std::string&)) = 0;
virtual void removeObserver(void(*callback)(const std::string&)) = 0;
// 主题状态改变时通知所有观察者
virtual void notifyObservers(const std::string& message) = 0;
};
// 具体主题类
class ConcreteSubject : public Subject {
private:
std::vector<void(*)(const std::string&)> observers;
public:
void registerObserver(void(*callback)(const std::string&)) override {
observers.push_back(callback);
}
void removeObserver(void(*callback)(const std::string&)) override {
observers.erase(std::remove(observers.begin(), observers.end(), callback), observers.end());
}
void notifyObservers(const std::string& message) override {
for (auto& observer : observers) {
observer(message);
}
}
// 状态改变的方法
void changeState(const std::string& newState) {
std::cout << "Subject state changed to: " << newState << std::endl;
notifyObservers(newState);
}
};
// 观察者类（这里直接使用全局函数作为回调）
void observerA(const std::string& message) {
std::cout << "Observer A received message: " << message << std::endl;
}
void observerB(const std::string& message) {
std::cout << "Observer B received message: " << message << std::endl;
}
int main() {
ConcreteSubject subject;
// 注册观察者
subject.registerObserver(observerA);
subject.registerObserver(observerB);
// 改变主题状态并触发通知
subject.changeState("New State");
return 0;
}