logging.cpp

namespace trillek {
namespace util {
namespace logging {
namespace detail {
	std::unique_ptr<logger> global_logger; 
}
}
}
}

logging.hpp

#ifndef LOGGING_HPP_INCLUDED
#define LOGGING_HPP_INCLUDED

#include <fstream>
#include <iostream>
#include <string>

#ifndef STRINGIFY
#define STRINGIFY(x) #x
#define TO_STRING(x) STRINGIFY(x)
#endif

#define LOG_LEVEL(lvl, message) ::trillek::util::logging::log(lvl, std::string(message) + "\t" __FILE__ ":" TO_STRING(__LINE__))
#define LOG(message) LOG_LEVEL(level::notice, message)
#define WARN(message) LOG_LEVEL(level::warning, message)
#define ERROR(message) LOG_LEVEL(level::error, message)

namespace trillek {
namespace util {
namespace logging {

enum class level {
    notice, warning, error
}

void init(std::string filename)
{
	detail::global_logger = std::make_unique<detail::logger>(filename);
}

namespace detail {
class logger {
public:
    logger(std::string filename);
    void log(level lvl, std::string message);
private:
    std::ofstream file;
};
}

}
}
}

#endif /* LOGGING_HPP_INCLUDED */

main.cpp

int main()
{
	// whatever
	::trillek::util::logging::init("trillek.log");
}