README
¶
slogan
slogan is a logger library for Golang.
Features :
- 10 Levels from "silent" to "trace", including POSIX levels
- Configurable format
- Configurable colors on individual items
- Easy elapsed time
Howto
Declare use
import (
"github.com/crownedgrouse/slogan"
)
An alias (here 'log') can be used by setting it before import :
import (
log "github.com/crownedgrouse/slogan"
)
Init
package main
import (
log "github.com/crownedgrouse/slogan"
)
func main() {
log.SetExitOnError(true)
// Set verbosity
log.SetVerbosity(log.Ltrace)
//
log.Runtime()
log.Trace(map[string]string{"this is a": "map"})
log.Debug("A debug message")
log.Info("An informative message")
log.Notice("A notification")
log.Warning("A warning")
log.Error("An Error")
log.Critical("A critical message")
log.Alert("An alert")
log.Emergency("An Emergency")
}
Will produce (color not visible in this example):
$ go build
$ ./main
debug OS:linux ARCH:386 CPU:4 COMPILER:gc ROOT:/home/eric/git/goroot
trace map[string]string
%v: map[this is a:map]
%v+: map[this is a:map]
%#v: map[string]string{"this is a":"map"}
debug A debug message
info An informative message
notice A notification
warning A warning
error An Error
debug Immediate exit with code 4
$ echo $?
4
Utilities
Show Runtime infos
Runtime informations can be easily shown as a debug level with a uniq call.
slogan.Runtime()
debug OS:linux ARCH:386 CPU:4 COMPILER:gc ROOT:/home/eric/git/goroot
Trace Go values
Call to Trace/1 will produce a trace log made of several lines. First line with 'trace' level and type of the value given. Below is written three usual ways to display Go values (%v, %v+ and %#v) separated with an empty line.
This format can be overrriden by your own preference (See 'Configuring/Formats' below).
slogan.Trace(Something)
Time elapsed
Display how many time elapsed since program start or since last call to ElapsedTime() .
// Show time elapsed since last call to ElapsedTime() or since beginning at first call
slogan.ElapsedTime()
// Show time elapsed since beginning. This will reset start time reference
slogan.AllDone()
Output will be a notice :
notice All done in : 296.538µs
Configuring
slogan can be configured at beginning of your program (and also at any time inside your program).
Tags
Tags can be changed by overwritting tags map, with GetTags/0 and SetTags/1.
var tags = [10]string{
"", // Prefix
"emergency", // 1
"alert ", // 2
"critical ", // 3
"error ", // 4
"warning ", // 5
"notice ", // 6
"info ", // 7
"debug ", // 8
"trace ", // 9
}
Output
Default output is on STDERR. Output can be set in a file by passing File Descriptor to "slogan".
f, err := os.OpenFile("/var/log/myown.log", os.O_RDWR|os.O_CREATE, 0755)
if err != nil {
log.Critical("Cannot open file")
}
log.SetOutput(f)
Color will be disabled if output is not a Terminal unless forcing it.
log.SetForceColor(true)
slogan is using legacy "log" package underneath. SetFlags can be used to change "log" parameters.
For instance to show caller and line number in code :
slogan.SetFlags(slogan.Lshortfile) // No need to import "log". Same constants used in "slogan".
Will produce something like below :
debug main.go:17 A debug message
info main.go:18 An informative message
notice main.go:20 A warning
error main.go:21 An Error
as well date/time information can be set this way.
Set a prefix to any log :
log.SetPrefix("===> ")
Behaviour
Considering Warning as Error (and potentialy exit) :
log.SetWarningAsError(true)
Set or change verbosity from 0 (silent) to 9 (debug) :
slogan.SetVerbosity(0) // Silent totally logs
slogan.SetVerbosity(slogan.Lsilent) // Same but using "slogan" Levels constant
By setting verbosity, all logs with level lower or equal will be generated (if no immediate exit on error was set and no error occured) :
log.SetExitOnError(true) // Exit if log level reach Error or worst.
If the case, the error message is generated and a debug level may appear, depending current verbosity, indicating that an immediate exit occured, and telling what is the program exit code. The exit code is equal to the level reached by the last fatal error, i.e 1 (emergency) to 4 (error) , or even 5 if warning considered error.
Set option to silent empty log messages :
slogan.SetNoEmpty(true) // Silent empty messages
Note: Exit on error is done even if message is empty and option set.
Formats
Formats can be configured by settings new "Sprintf" values to the three arguments passed to slogan functions :
- tag %[1]s
- log %[2]s
- caller (path:line) %[3]s (only if caller is required in "log" parameters)
// Get current map
formats := slogan.GetFormats()
// Override format for caller : set caller in first
formats["caller"]= "%-25[3]s %[1]s %[2]s "
slogan.SetFormats(formats)
slogan.SetFlags(log.Lshortfile) // caller is required to be shown
Default formats are :
var formats = map[string]string{
"fatal" : "Immediate exit with code %d", // immediate exit on error format
"trace" : "%[1]T\n %%v: %[1]v\n\n%%v+: %+[1]v\n\n%%#v: %#[1]v", // multiline trace format
"empty" : "%#v", // trace format for empty variable (avoid unuseful multiline)
"runtime" : "OS:%s ARCH:%s CPU:%d COMPILER:%s ROOT:%s", // runtime infos format
"default" : " %[1]s %[2]s", // default log format
"caller" : " %[1]s %[3]s\t %[2]s", // default log format with caller (where)
"where" : "%s:%d", // format for caller location path:linenumber
"alldone" : "All done in : %s", // all done time format
"elapsed" : "Elapsed time : %s", // elapsed time format
}
Colors
Color will be disabled if output is not a terminal. This can be avoid however by calling SetForceColor/1 .
Colors can be changed by overwritting colors map, with GetColors/0 and SetColors/1.
See here for possible colors and other output (reverse, underlining, etc.)
var colors = map[int]string{
10: "Underline", // Caller
9: "DarkGray", // trace
8: "DarkGray", // debug
7: "Purple", // info
6: "Green", // notice
5: "Yellow", // warning
4: "LightRed", // error
3: "Red", // critical
2: "BLightRed", // alert
1: "BRed", // emergency
0: "", // Prefix
}
As well colorization of elements (called 'parts') in log line can be tuned by changing parts map, with GetParts/0 and SetParts/1
var parts = map[string]bool{
"caller": true, // colorize caller (event if it is underlining)
"tag": true, // colorize tag
"log": false, // do not colorize log entry
"prefix": false, // do not colorize prefix
}
Documentation
¶
Overview ¶
slogan is a logger library for Golang.
Index ¶
- Constants
- Variables
- func Alert(log string)
- func AllDone()
- func Critical(log string)
- func Debug(log string)
- func ElapsedTime()
- func Emergency(log string)
- func Error(log string)
- func GetColors() map[int]string
- func GetFormats() map[string]string
- func GetParts() map[string]bool
- func GetTags() [10]string
- func Info(log string)
- func IsTerminal() bool
- func Log(level int, log string)
- func Notice(log string)
- func Runtime()
- func SetColor(mode bool)
- func SetColors(n map[int]string) map[int]string
- func SetExitOnError(mode bool)
- func SetFlags(flag int)
- func SetForceColor(mode bool)
- func SetFormats(n map[string]string) map[string]string
- func SetNoEmpty(mode bool)
- func SetOutput(w io.Writer)
- func SetParts(n map[string]bool) map[string]bool
- func SetPrefix(prefix string) string
- func SetTags(n [10]string) [10]string
- func SetTraceCaller(mode bool)
- func SetVerbosity(level int)
- func SetWarningAsError(mode bool)
- func ShowColors()
- func ShowFormats()
- func ShowParts()
- func ShowTags()
- func Silent(log string)
- func Trace(trace interface{})
- func TraceCall(trace interface{})
- func TraceCall_(trace interface{})
- func Trace_(trace interface{})
- func Warning(log string)
Constants ¶
const ( Lsilent = 0 Lemergency = 1 Lalert = 2 Lcritical = 3 Lerror = 4 Lwarning = 5 Lnotice = 6 Linfo = 7 Ldebug = 8 Ltrace = 9 )
Contants for log levels
const ( Ldate = log.Ldate Ltime = log.Ltime Lmicroseconds = log.Lmicroseconds Llongfile = log.Llongfile Lshortfile = log.Lshortfile LUTC = log.LUTC LstdFlags = log.Ldate | log.Ltime )
Contants for legacy log package
Variables ¶
var CallerBase bool = true
should show only basename of caller
var Colorize bool = true
should colorize ?
var ExitOnError bool = false
should exit on error ?
var ForceColorize bool = false
should colorize even if output is not a terminal ?
var NoEmpty bool = false
should empty log string logged ?
var TraceCaller bool = false
should trace caller ?
var Verbosity int = Lwarning
verbosity
var WarningAsError bool = false
should warning be error ?
Functions ¶
func ElapsedTime ¶
func ElapsedTime()
Notice Time elapsed since last call to this function or since start otherwise and reset time reference
func SetFormats ¶
Set a new format map and return former map
func SetNoEmpty ¶
func SetNoEmpty(mode bool)
func TraceCall_ ¶
func TraceCall_(trace interface{})
Silent trace and avoid 'declared and not used' build errors
Types ¶
This section is empty.
Source Files