C++ Pass Boost::log severity level as argument to function - c++

Question

I want to have only one function to write logs which would parse ellipsis and send result to the Boost::log, based on severity level. In header file would be defined different macros, which would select a correct severity level. There is the code:
#include <boost/log/core.hpp>
#include <boost/log/trivial.hpp>
#include <boost/log/expressions.hpp>
#define DEBUG(msg, ...) Logger::write_log(debug, msg, ##__VA_ARGS__);
#define INFO(msg, ...) Logger::write_log(info, msg, ##__VA_ARGS__);
#define WARNING(msg, ...) Logger::write_log(warning, msg, ##__VA_ARGS__);
#define ERROR(msg, ...) Logger::write_log(error, msg, ##__VA_ARGS__);
namespace logging = boost::log;
void write_log(auto level, const char *message, ...)
{
char buffer[512];
va_list args;
// Parse ellipsis and add arguments to message
va_start (args, message);
vsnprintf (buffer, sizeof(buffer), message, args);
va_end (args);
BOOST_LOG_TRIVIAL(level) << buffer;
}
int main(int argc, char** argv)
{
DEBUG("Test string %s", "additional string");
return 0;
}
But during compilation I get the next error:
error: 'level' is not a member of 'boost::log::v2s_mt_nt5::trivial'
BOOST_LOG_TRIVIAL(level) << buffer;
Seems that my level argument have an incorrect type. I also tried to use logging::trivial::severity_level level instead of auto level, but this didn't help. How can I fix this error?
UPDATED:
there is working solution:
#include <boost/log/core.hpp>
#include <boost/log/trivial.hpp>
#include <boost/log/expressions.hpp>
#define DEBUG(msg, ...) Logger::write_log(debug, msg, ##__VA_ARGS__);
#define INFO(msg, ...) Logger::write_log(info, msg, ##__VA_ARGS__);
#define WARNING(msg, ...) Logger::write_log(warning, msg, ##__VA_ARGS__);
#define ERROR(msg, ...) Logger::write_log(error, msg, ##__VA_ARGS__);
namespace logging = boost::log;
enum severity_level
{
debug,
info,
warning,
error,
exception
};
src::severity_logger<severity_level> slg;
void write_log(severity_level level, const char *message, ...)
{
char buffer[512];
va_list args;
// Parse ellipsis and add arguments to message
va_start (args, message);
vsnprintf (buffer, sizeof(buffer), message, args);
va_end (args);
BOOST_LOG_SEV(slg, level) << buffer;
}
int main(int argc, char** argv)
{
DEBUG("Test string %s", "additional string");
return 0;
}

Answer 1

Follow boost log example and define:
// severity levels
enum severity_level
{
trace,
debug,
info,
warning,
error,
fatal
};
And you need to make your function to accept proper type:
void write_log(severity_level level, const char *message, ...){ ... }
Another option:
#include <boost/log/core.hpp>
#include <boost/log/trivial.hpp>
#include <boost/log/expressions.hpp>
#define DEBUG(msg, ...) Logger::write_log(logging::trivial::debug, msg, ##__VA_ARGS__);
#define INFO(msg, ...) Logger::write_log(logging::trivial::info, msg, ##__VA_ARGS__);
#define WARNING(msg, ...) Logger::write_log(logging::trivial::warning, msg, ##__VA_ARGS__);
#define ERROR(msg, ...) Logger::write_log(logging::trivial::error, msg, ##__VA_ARGS__);
namespace logging = boost::log;
#define LOG_TRIVIAL(lvl)\
BOOST_LOG_STREAM_WITH_PARAMS(::boost::log::trivial::logger::get(),\
(::boost::log::keywords::severity = lvl))
void write_log(logging::trivial::severity_level level, const char *message, ...)
{
char buffer[512];
va_list args;
// Parse ellipsis and add arguments to message
va_start(args, message);
vsnprintf(buffer, sizeof(buffer), message, args);
va_end(args);
LOG_TRIVIAL(level) << buffer;
}
int main(int argc, char** argv)
{
DEBUG("Test string %s", "additional string");
return 0;
}

Answer 2

My advice: create your own severity. It's just an enum! Follow the source code of that "level" (using your IDE) to see that it's a simple enum. Copy it to your implementation, and change it as necessary. This is how it looks (after changing its name):
enum my_severity_level
{
trace,
debug,
info,
warning,
error,
fatal
};
Take that to your code, and use it as necessary.
That write_log function should be like this:
void write_log(my_severity_level level, const char *message, ...) { ... }