Simple Global Logger

logger.cpp

#include "logger.h"

Logger Logger::instance_;

void Logger::log()
{
    //...
}

logger.h

#pragma once

class Logger
{
public:
    static Logger& instance()
    {
        return instance_;
    }
    
    void log(const char *msg);

    // void configure(...); etc

private:
    Logger();

    static Logger instance_;
};

#define LOG(msg) Logger::instance().log(msg)