lgr

README

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).

Documentation

Index

• Variables
• func Caller(l *Logger)
• func Debug(l *Logger)
• func Printf(format string, args ...interface{})
• func Setup(opts ...Option)
• type Func
  • func (f Func) Logf(format string, args ...interface{})
• type L
  • func Default() L
• type Logger
  • func New(options ...Option) *Logger
  • func (l *Logger) Logf(format string, args ...interface{})
• type Option
  • func Err(w io.Writer) Option
  • func Out(w io.Writer) Option

Variables

var NoOp = Func(func(format string, args ...interface{}) {})

NoOp logger

var Std = Func(func(format string, args ...interface{}) { stdlog.Printf(format, args...) })

Std logger sends to std default logger directly

Functions

func Caller

func Caller(l *Logger)

Caller adds caller info with func, file, and line number

func Debug

func Debug(l *Logger)

Debug turn on dbg mode

func Printf

func Printf(format string, args ...interface{})

Printf simplifies replacement of std logger

func Setup

func Setup(opts ...Option)

Setup default logger with options

Types

type Func

type Func func(format string, args ...interface{})

Func type is an adapter to allow the use of ordinary functions as Logger.

func (Func) Logf

func (f Func) Logf(format string, args ...interface{})

Logf calls f(id)

type L

type L interface {
	Logf(format string, args ...interface{})
}

L defines minimal interface used to log things

func Default

func Default() L

Default returns pre-constructed def logger (debug on, callers disabled)

type Logger

type Logger struct {
	// contains filtered or unexported fields
}

Logger provided simple logger with basic support of levels. Thread safe

func New

func New(options ...Option) *Logger

New makes new leveled logger. Accepts dbg flag turing on info about the caller and allowing DEBUG messages/ Two writers can be passed optionally - first for out and second for err

func (*Logger) Logf

func (l *Logger) Logf(format string, args ...interface{})

Logf implements L interface to output with printf style. Each line prefixed with ts, level and optionally (dbg mode only) by caller info. ERROR and FATAL also send the same line to err writer. FATAL adds runtime stack and os.exit(1), like panic.

type Option

type Option func(l *Logger)

Option func type

func Err

func Err(w io.Writer) Option

Err sets error writer

func Out

func Out(w io.Writer) Option

Out sets out writer