boost/libs/log/example/keywords/main.cpp

/*
 *          Copyright Andrey Semashev 2007 - 2015.
 * Distributed under the Boost Software License, Version 1.0.
 *    (See accompanying file LICENSE_1_0.txt or copy at
 *          http://www.boost.org/LICENSE_1_0.txt)
 */
/*!
 * \file   main.cpp
 * \author Andrey Semashev
 * \date   01.12.2012
 *
 * \brief  An example of using attribute keywords.
 */

// #define BOOST_LOG_USE_CHAR
// #define BOOST_ALL_DYN_LINK 1
// #define BOOST_LOG_DYN_LINK 1

#include <iostream>

#include <boost/log/common.hpp>
#include <boost/log/expressions.hpp>

#include <boost/log/utility/setup/file.hpp>
#include <boost/log/utility/setup/console.hpp>
#include <boost/log/utility/setup/common_attributes.hpp>

#include <boost/log/attributes/timer.hpp>
#include <boost/log/attributes/named_scope.hpp>

#include <boost/log/sources/logger.hpp>

#include <boost/log/support/date_time.hpp>

namespace logging = boost::log;
namespace sinks = boost::log::sinks;
namespace attrs = boost::log::attributes;
namespace src = boost::log::sources;
namespace expr = boost::log::expressions;
namespace keywords = boost::log::keywords;

using boost::shared_ptr;

// Here we define our application severity levels.
enum severity_level
{
    normal,
    notification,
    warning,
    error,
    critical
};

// The formatting logic for the severity level
template< typename CharT, typename TraitsT >
inline std::basic_ostream< CharT, TraitsT >& operator<< (
    std::basic_ostream< CharT, TraitsT >& strm, severity_level lvl)
{
    static const char* const str[] =
    {
        "normal",
        "notification",
        "warning",
        "error",
        "critical"
    };
    if (static_cast< std::size_t >(lvl) < (sizeof(str) / sizeof(*str)))
        strm << str[lvl];
    else
        strm << static_cast< int >(lvl);
    return strm;
}

// Declare attribute keywords
BOOST_LOG_ATTRIBUTE_KEYWORD(_severity, "Severity", severity_level)
BOOST_LOG_ATTRIBUTE_KEYWORD(_timestamp, "TimeStamp", boost::posix_time::ptime)
BOOST_LOG_ATTRIBUTE_KEYWORD(_uptime, "Uptime", attrs::timer::value_type)
BOOST_LOG_ATTRIBUTE_KEYWORD(_scope, "Scope", attrs::named_scope::value_type)

int main(int argc, char* argv[])
{
    // This is a simple tutorial/example of Boost.Log usage

    // The first thing we have to do to get using the library is
    // to set up the logging sinks - i.e. where the logs will be written to.
    logging::add_console_log(std::clog, keywords::format = "%TimeStamp%: %_%");

    // One can also use lambda expressions to setup filters and formatters
    logging::add_file_log
    (
        "sample.log",
        keywords::filter = _severity >= warning,
        keywords::format = expr::stream
            << expr::format_date_time(_timestamp, "%Y-%m-%d, %H:%M:%S.%f")
            << " [" << expr::format_date_time(_uptime, "%O:%M:%S")
            << "] [" << expr::format_named_scope(_scope, keywords::format = "%n (%f:%l)")
            << "] <" << _severity
            << "> " << expr::message
/*
        keywords::format = expr::format("%1% [%2%] [%3%] <%4%> %5%")
            % expr::format_date_time(_timestamp, "%Y-%m-%d, %H:%M:%S.%f")
            % expr::format_date_time(_uptime, "%O:%M:%S")
            % expr::format_named_scope(_scope, keywords::format = "%n (%f:%l)")
            % _severity
            % expr::message
*/
    );

    // Also let's add some commonly used attributes, like timestamp and record counter.
    logging::add_common_attributes();
    logging::core::get()->add_thread_attribute("Scope", attrs::named_scope());

    BOOST_LOG_FUNCTION();

    // Now our logs will be written both to the console and to the file.
    // Let's do a quick test and output something. We have to create a logger for this.
    src::logger lg;

    // And output...
    BOOST_LOG(lg) << "Hello, World!";

    // Now, let's try logging with severity
    src::severity_logger< severity_level > slg;

    // Let's pretend we also want to profile our code, so add a special timer attribute.
    slg.add_attribute("Uptime", attrs::timer());

    BOOST_LOG_SEV(slg, normal) << "A normal severity message, will not pass to the file";
    BOOST_LOG_SEV(slg, warning) << "A warning severity message, will pass to the file";
    BOOST_LOG_SEV(slg, error) << "An error severity message, will pass to the file";

    return 0;
}