lgr - simple logger with some extras

install

go get github/go-pkgz/lgr

usage

    l := lgr.New(lgr.Debug, lgr.Caller) // allow debug and caller info
    l.Logf("INFO some important err message, %v", err)
    l.Logf("DEBUG some less important err message, %v", err)

output looks like this:

2018/01/07 13:02:34.000 INFO  {svc/handler.go:101 h.MyFunc1} some important err message, can't open file`
2018/01/07 13:02:34.015 DEBUG {svc/handler.go:155 h.MyFunc2} some less important err message, file is too small`

Without lgr.Caller it will drop {caller} part

details

interfaces and default loggers

lgr package provides a single interface lgr.L with a single method Logf(format string, args ...interface{}). Function wrapper lgr.Func allows to make lgr.L from a function directly.
Default logger functionality can be used without lgr.New, but just lgr.Printf
Two predefined loggers available: lgr.NoOp (do-nothing logger) and lgr.Std (passing directly to stdlib log)

options

lgr.New call accepts functional options:

lgr.Debug - turn debug mode on. This allows messages with "DEBUG" level (filtered overwise)
lgr.Caller - adds the caller info each message
lgr.Out(io.Writer) - sets the output writer, default os.Stdout
lgr.Err(io.Writer) - sets the error writer, default os.Stderr

levels

lgr.Logf recognizes prefixes like "INFO" or "[INFO]" as levels. The full list of supported levels - "DEBUG", "INFO", "WARN", "ERROR", "PANIC" and "FATAL"

DEBUG will be filtered unless lgr.Debug option defined
INFO and WARN don't have any special behavior attached
ERROR sends messages to both out and err writers
"PANIC" and "FATAL" send messages to both out and err writers. In addition sends dump of callers and runtime info to err only, and call os.Exit(1).