How can I add the console (stdout) as a sink in g3log? - c++

Question

I am new to g3log. I compiled and ran one of the examples I found in the repo, but was not able to ,modify it to print the log messages to the console rather than a file.
The following lines from the example set the logger:
auto worker = g3::LogWorker::createLogWorker();
auto handle= worker->addDefaultLogger(argv[0], path_to_log_file);
g3::initializeLogging(worker.get());
Where the line in the middle sets the prefix of the log and gives the path where the log file should be created.
How can I modify this code to print to the console\both the console and the file?
Thanks,
Omer.

Answer 1

You could define a customized sink class with a message receiver function that forward the
stripped message to console without formatting. Below is simplest form of the implementation:
class CustomSink {
public:
void forwardLogToStdout(g3::LogMessageMover logEntry) {
std::cout << logEntry.get().message() << std::endl;
}
};
So, in your code, you only need to replacing the worker->addDefaultLogger(...) by this snippet:
auto handle = worker->addSink(std::make_unique<CustomSink>(), &CustomSink::forwardLogToStdout);

Answer 2

from g3log github to implement colored console output you need:
struct ColorCoutSink {
// Linux xterm color
// http://stackoverflow.com/questions/2616906/how-do-i-output-coloured-text-to-a-linux-terminal
enum FG_Color {YELLOW = 33, RED = 31, GREEN=32, WHITE = 97};
FG_Color GetColor(const LEVELS level) const
{
if (level.value == WARNING.value) { return YELLOW; }
if (level.value == DEBUG.value) { return GREEN; }
if (g3::internal::wasFatal(level)) { return RED; }
return WHITE;
}
void ReceiveLogMessage(g3::LogMessageMover logEntry)
{
auto level = logEntry.get()._level;
auto color = GetColor(level);
std::cout << "\033[" << color << "m" << logEntry.get().toString() << "\033[m" << std::endl;
}
};
// in main.cpp, main() function
auto sinkHandle = logworker->addSink(std::make_unique<CustomSink>(),
&CustomSink::ReceiveLogMessage);
So if you remove color "things", the logger will output to console