C++类与接口分离实现灵活架构设计

class Logger {
public:
    virtual ~Logger() = default;
    virtual void log(const std::string& message) = 0;
};

class FileLogger : public Logger {
public:
    void log(const std::string& message) override {
        // 写入文件
        std::ofstream file("log.txt", std::ios::app);
        file << message << std::endl;
    }
};
class ConsoleLogger : public Logger {
public:
void log(const std::string& message) override {
std::cout << "[LOG] " << message << std::endl;
}
};

class UserService {
    Logger* logger;
public:
    UserService(Logger* l) : logger(l) {}
void addUser(const std::string& name) {
    // 业务逻辑
    logger->log("User added: " + name);
}
};

std::unique_ptr<Logger> createLogger(const std::string& type) {
    if (type == "file") return std::make_unique<FileLogger>();
    if (type == "console") return std::make_unique<ConsoleLogger>();
    return nullptr;
}