C++ Logging Class

Format.cpp

#include "Format.hpp"
#include <iomanip>

std::ostream& operator<<(std::ostream& out, std::tm* dt)
{
    return out // ISO 8601 without timezone
        << std::setfill('0') << std::setw(4) << dt->tm_year + 1900 << "-"
        << std::setfill('0') << std::setw(2) << dt->tm_mday << "-"
        << std::setfill('0') << std::setw(2) << dt->tm_mon + 1 << " "
        << std::setfill('0') << std::setw(2) << dt->tm_hour << ":"
        << std::setfill('0') << std::setw(2) << dt->tm_min << ":"
        << std::setfill('0') << std::setw(2) << dt->tm_sec;
}

Format.hpp

#pragma once

#include <ctime>
#include <ostream>

std::ostream& operator<<(std::ostream& out, std::tm* dt);

Log.cpp

#include "Format.hpp"
#include "Log.hpp"
#include <ctime>
#include <iostream>

int Log::Buffer::sync()
{
    auto ts = std::time(0);
    _log._out << "[" << std::localtime(&ts) << "] " << str();
    if (_log._console) std::cout << str();

    str("");
    return 0;
}

bool Log::open(std::string const& file)
{
    _file = file;
    _out.open(file.c_str());
    return _out.is_open();
}

Log.hpp

#pragma once

#include <fstream>
#include <ostream>
#include <sstream>
#include <string>

// Log: A std::ofstream that prefixes every message (text between flushes) with
// the current time. Note, you must use std::endl for terminating lines in order
// for the time stamp to be written before each line.
//
// Messages can optionally be output to stdout as well.
class Log : NonCopyable, public std::ostream {
public:
    Log()
        : std::ostream(&_buffer)
        , _buffer(*this)
        , _console(false)
    {}

    Log(std::string const& file, bool console = false)
        : std::ostream(&_buffer)
        , _buffer(*this)
        , _file(file)
        , _out(file.c_str())
        , _console(console)
    {}

    bool open(std::string const& file);
    void close() { _out.close(); }
    bool isOpen() const { return _out.is_open(); }

    std::string const& file() const { return _file; }
    bool console() const { return _console; }
    void console(bool c) { _console = c; }

private:
    // Buffer: A std::stringbuf that outputs the time stamp and message to a
    // Log's _out upon being synced.
    class Buffer : public std::stringbuf {
    public:
        Buffer(Log& log)
            : _log(log)
        {}

        int sync();

    private:
        Log& _log;
    };
    friend class Buffer;

    Buffer _buffer;
    std::string _file;
    std::ofstream _out;
    bool _console;
};