A light-weight, header only C++ logger to be used anywhere in any project.

Author: Samuel Lewis
Updated: 12th Feb 2018
Version: 2.0

github.com/Samuel-Lewis/LightLogger

In any file you want to log within, include

#include "light_logger.h"

and you're done! All the below setup is optional.

To control the logging level, you need to define LOG_LEVEL to some level you want to log at. Levels available are:

FATAL
ERROR
WARNING
INFO
DEBUG

If no level is set, the default is INFO. Extra levels can be added or removed by editing the kLogLevel struct within this file.

The recommended way to set the level is during compile time, by including as a flag. Eg:

-DLOG_LEVEL=INFO

Alternatively, you could define it in the code base before you include light_logger.h for the first time. Eg:

#define LOG_LEVEL WARNING
#include "light_logger.h"

By default, if you ever log a FATAL, the program will log the message and then exit with return EXIT_FAILURE. You can change the level to exit at by defining LOG_DIE_LEVEL.

-DLOG_DIE_LEVEL=ERROR

Each log message is prefaced by a timestamp of when the message was called. To change the format, you can specify LOG_TIME_FORMAT to be some format string. The rules are as follows here http://www.cplusplus.com/reference/iomanip/put_time/. By default, the format is "%T", (14:55:02)

-DLOG_TIME_FORMAT="%D %R"

If your system does not support ANSI escape codes, or you want to log to plain text, make sure to define the flag LOG_DISABLE_ANSI at compile time.

Log something to a logging level:

LOG(INFO) << "Your message here " << FooBar();

Quick sanity check some expression:

CHECK_THAT(!my_string.empty());

Print out some variable and its value:

LOOK(my_string);

When you want to print out a line to your logs, use the LOG(level) command, where level is one of the listed levels above. This acts as a stream that you can then send things to. Eg:

LOG(INFO) << "Your message here " << FooBar();

All logs will be flushed to stderr as soon as the call log is completed. Anything you send to the stream must be compatible with standard C++ streams.

CHECK_THAT(expression) is much like an ASSERT, and will cause an ERROR message should the expression evaluate to false. If it evaluates to true, no message will be logged.

CHECK_THAT(a != b);

LOOK(my_var) is a quick utility that pretty much aliases printing out the variable name and then the variable value. This will only accept variables, no literals. Use as such:

LOOK(my_name);