C++ 框架中可重用代码的精髓：设计原则与实践

// 枚举日志级别
enum class LogLevel { Debug, Info, Warning, Error, Critical };

// 抽象日志记录器
class Logger {
public:
    virtual void log(LogLevel level, const std::string& message) = 0;
};

// 抽象日志工厂
class LoggerFactory {
public:
    virtual std::unique_ptr<Logger> createLogger(LogLevel level) = 0;
};

// 具体的日志记录器实现
class ConsoleLogger : public Logger {
public:
    void log(LogLevel level, const std::string& message) override {
        // 将日志消息输出到控制台
    }
};

// 具体的日志工厂实现
class DefaultLoggerFactory : public LoggerFactory {
public:
    std::unique_ptr<Logger> createLogger(LogLevel level) override {
        switch (level) {
            case LogLevel::Debug:
            case LogLevel::Info:
                return std::make_unique<ConsoleLogger>();
            default:
                // 返回一个默认的日志记录器
                return nullptr;
        }
    }
};

// 使用日志记录框架
class MyClass {
private:
    std::unique_ptr<Logger> logger;

public:
    MyClass(LoggerFactory* factory) {
        logger = factory->createLogger(LogLevel::Info);
    }

    void logMessage(const std::string& message) {
        logger->log(LogLevel::Info, message);
    }
};