mul_loggers_one_filter.cpp

This usage:

• You have several loggers
• You have one filter, which can be turned on or off
• You want to format the message before it's written
• Each logger has several log destinations

Optimizations:

• use a cache string (from optimize namespace), in order to make formatting the message faster

Logs:

• Error messages go into err.txt file
  • formatting - prefix each message by time, index, and append newline
• Info output goes to console, and a file called out.txt
  • formatting - prefix each message by time, "[app]", and append newline
• Debug messages go to the debug output window, and the console
  • formatting - prefix each message by "[dbg]", time, and append newline

Here's how the output will look like:

The debug output window:

18:59.24 [dbg] this is so cool 1
18:59.24 [dbg] this is so cool again 2

The console:

18:59.24 [dbg] this is so cool 1
18:59.24 [dbg] this is so cool again 2
18:59.24 [app] hello, world
18:59.24 [app] good to be back ;) 4

The out.txt file:

18:59.24 [app] hello, world
18:59.24 [app] good to be back ;) 4

The err.txt file

18:59.24 [1] first error 3
18:59.24 [2] second error 5

#include <boost/logging/format_fwd.hpp>

BOOST_LOG_FORMAT_MSG( optimize::cache_string_one_str<> )

#include <boost/logging/format.hpp>
using namespace boost::logging;

typedef logger_format_write< > logger_type;

BOOST_DECLARE_LOG_FILTER(g_log_filter, filter::no_ts ) 
BOOST_DECLARE_LOG(g_log_err, logger_type) 
BOOST_DECLARE_LOG(g_log_app, logger_type)
BOOST_DECLARE_LOG(g_log_dbg, logger_type)

#define LDBG_ BOOST_LOG_USE_LOG_IF_FILTER(g_log_dbg(), g_log_filter()->is_enabled() ) << "[dbg] "
#define LERR_ BOOST_LOG_USE_LOG_IF_FILTER(g_log_err(), g_log_filter()->is_enabled() )
#define LAPP_ BOOST_LOG_USE_LOG_IF_FILTER(g_log_app(), g_log_filter()->is_enabled() ) << "[app] "

BOOST_DEFINE_LOG_FILTER(g_log_filter, filter::no_ts ) 
BOOST_DEFINE_LOG(g_log_err, logger_type)
BOOST_DEFINE_LOG(g_log_app, logger_type)
BOOST_DEFINE_LOG(g_log_dbg, logger_type)

void mul_logger_one_filter_example() {
    // Err log
    g_log_err()->writer().add_formatter( formatter::idx(), "[%] "  );
    g_log_err()->writer().add_formatter( formatter::time("$hh:$mm.$ss ") );
    g_log_err()->writer().add_formatter( formatter::append_newline() );
    g_log_err()->writer().add_destination( destination::file("err.txt") );

    // App log
    g_log_app()->writer().add_formatter( formatter::time("$hh:$mm.$ss ") );
    g_log_app()->writer().add_formatter( formatter::append_newline() );
    g_log_app()->writer().add_destination( destination::file("out.txt") );
    g_log_app()->writer().add_destination( destination::cout() );

    // Debug log
    g_log_dbg()->writer().add_formatter( formatter::time("$hh:$mm.$ss ") );
    g_log_dbg()->writer().add_formatter( formatter::append_newline() );
    g_log_dbg()->writer().add_destination( destination::dbg_window() );
    g_log_dbg()->writer().add_destination( destination::cout() );

    g_log_app()->mark_as_initialized();
    g_log_err()->mark_as_initialized();
    g_log_dbg()->mark_as_initialized();

    int i = 1;
    LDBG_ << "this is so cool " << i++;
    LDBG_ << "this is so cool again " << i++;
    LERR_ << "first error " << i++;

    std::string hello = "hello", world = "world";
    LAPP_ << hello << ", " << world;

    g_log_filter()->set_enabled(false);
    LDBG_ << "this will not be written anywhere";
    LAPP_ << "this won't be written anywhere either";
    LERR_ << "this error is not logged " << i++;

    g_log_filter()->set_enabled(true);
    LAPP_ << "good to be back ;) " << i++;
    LERR_ << "second error " << i++;
}




int main() {
    mul_logger_one_filter_example();
}


// End of file

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Copyright John Torjo © 2007
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