Package llog implements level-restricted logging. It is similar and based to standard log package but provides additional flexibility in management of logging messages.
Package provides 5 levels of logging:
DEBUG - output all messages (lowest level)
INFO - output all messages except debug messages
WARNING - output all messages except debug and info messages - it is default level
ERROR - output only error and critical messages
CRITICAL - output only critical messages (highest level)
There is a standard logger that initialized with os.Stderr as output, "" as prefix, log.LstdFlags (see https://golang.org/pkg/log/#pkg-constants for details) as flags, and WARNING as logging level.
Logging level of standard logger can be changed via SetLevel(level int). Use constants DEBUG, INFO, WARNING, ERROR or CRITICAL for setting the level value. You can also change output: SetOutput(w io.Writer), log message prefix: SetPrefix(prefix string), and message format flags: SetFlags(flag int) (see https://golang.org/pkg/log/#pkg-constants for details about flags).
To create a new log message of the required logging level you have to use one of the following functions:
Debug(v ...interface{}) // equal to log.Println() when logging level is DEBUG
Info(v ...interface{}) // equal to log.Println() when logging level is INFO or less
Warning(v ...interface{}) // equal to log.Println() when logging level is WARNING or less
Error(v ...interface{}) // equal to log.Println() when logging level is ERROR or less
Critical(v ...interface{}) // equal to log.Panicln() in any logging level
Debugf(format string, v ...interface{}) // equal to log.Printf() when logging level is DEBUG
Infof(format string, v ...interface{}) // equal to log.Printf() when logging level is INFO or less
Warningf(format string, v ...interface{}) // equal to log.Printf() when logging level is WARNING or less
Errorf(format string, v ...interface{}) // equal to log.Printf() when logging level is ERROR or less
Criticalf(format string, v ...interface{}) // equal to log.Panicf() in any logging level
Output of the functions will be additionally tagged with one letter identifier of logging level of the message: D(EBUG), I(NFO), W(ARNING), E(RROR) or C(RITICAL). For example:
Warning("Some message") // Output: W: Some message
When the current logging level is greater than level of created message then function do nothing.
New() allows to create the new Logger that has the same methods as standard logger.
NOTE: as llog.Logger is just extension of log.Logger the full set of log package methods/functions/constants are available to use together with llog methods. But standard logger has only llog declared methods.