README
¶
jWalterWeatherman
Seamless printing to the terminal (stdout) and logging to a io.Writer (file) that’s as easy to use as fmt.Println.
Graphic by JonnyEtc
JWW is primarily a wrapper around the excellent standard log library. It provides a few advantages over using the standard log library alone.
- Ready to go out of the box.
- One library for both printing to the terminal and logging (to files).
- Really easy to log to either a temp file or a file you specify.
I really wanted a very straightforward library that could seamlessly do the following things.
- Replace all the println, printf, etc statements thought my code with something more useful
- Allow the user to easily control what levels are printed to stdout
- Allow the user to easily control what levels are logged
- Provide an easy mechanism (like fmt.Println) to print info to the user which can be easily logged as well
- Due to 2 & 3 provide easy verbose mode for output and logs
- Not have any unnecessary initialization cruft. Just use it.
Usage
Step 1. Use it
Put calls throughout your source based on type of feedback. No initialization or setup needs to happen. Just start calling things.
Available Loggers are:
- TRACE
- DEBUG
- INFO
- WARN
- ERROR
- CRITICAL
- FATAL
These each are loggers based on the log standard library and follow the standard usage. Eg..
import (
jww "github.com/spf13/jwalterweatherman"
)
...
if err != nil {
// This is a pretty serious error and the user should know about
// it. It will be printed to the terminal as well as logged under the
// default thresholds.
jww.ERROR.Println(err)
}
if err2 != nil {
// This error isn’t going to materially change the behavior of the
// application, but it’s something that may not be what the user
// expects. Under the default thresholds, Warn will be logged, but
// not printed to the terminal.
jww.WARN.Println(err2)
}
// Information that’s relevant to what’s happening, but not very
// important for the user. Under the default thresholds this will be
// discarded.
jww.INFO.Printf("information %q", response)
Why 7 levels?
Maybe you think that 7 levels are too much for any application... and you are probably correct. Just because there are seven levels doesn’t mean that you should be using all 7 levels. Pick the right set for your needs. Remember they only have to mean something to your project.
Step 2. Optionally configure JWW
Under the default thresholds :
- Debug, Trace & Info goto /dev/null
- Warn and above is logged (when a log file/io.Writer is provided)
- Error and above is printed to the terminal (stdout)
Changing the thresholds
The threshold can be changed at any time, but will only affect calls that execute after the change was made.
This is very useful if your application has a verbose mode. Of course you can decide what verbose means to you or even have multiple levels of verbosity.
import (
jww "github.com/spf13/jwalterweatherman"
)
if Verbose {
jww.SetLogThreshold(jww.LevelTrace)
jww.SetStdoutThreshold(jww.LevelInfo)
}
Note that JWW's own internal output uses log levels as well, so set the log level before making any other calls if you want to see what it's up to.
Using a temp log file
JWW conveniently creates a temporary file and sets the log Handle to a io.Writer created for it. You should call this early in your application initialization routine as it will only log calls made after it is executed. When this option is used, the library will fmt.Println where to find the log file.
import (
jww "github.com/spf13/jwalterweatherman"
)
jww.UseTempLogFile("YourAppName")
Setting a log file
JWW can log to any file you provide a path to (provided it’s writable). Will only append to this file.
import (
jww "github.com/spf13/jwalterweatherman"
)
jww.SetLogFile("/path/to/logfile")
More information
This is an early release. I’ve been using it for a while and this is the third interface I’ve tried. I like this one pretty well, but no guarantees that it won’t change a bit.
I wrote this for use in hugo. If you are looking for a static website engine that’s super fast please checkout Hugo.
Documentation
¶
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ( TRACE *log.Logger DEBUG *log.Logger INFO *log.Logger WARN *log.Logger ERROR *log.Logger CRITICAL *log.Logger FATAL *log.Logger LOG *log.Logger FEEDBACK Feedback LogHandle io.Writer = ioutil.Discard OutHandle io.Writer = os.Stdout BothHandle io.Writer = io.MultiWriter(LogHandle, OutHandle) NotePads []*NotePad = []*NotePad{trace, debug, info, warn, err, critical, fatal} DATE = log.Ldate TIME = log.Ltime SFILE = log.Lshortfile LFILE = log.Llongfile MSEC = log.Lmicroseconds )
Functions ¶
func SetLogFile ¶
func SetLogFile(path string)
Conveniently Sets the Log Handle to a io.writer created for the file behind the given filepath Will only append to this file
func SetLogFlag ¶
func SetLogFlag(flags int)
Set the log Flags (Available flag: DATE, TIME, SFILE, LFILE and MSEC)
func SetLogThreshold ¶
func SetLogThreshold(level Level)
Establishes a threshold where anything matching or above will be logged
func SetStdoutThreshold ¶
func SetStdoutThreshold(level Level)
Establishes a threshold where anything matching or above will be output
func UseTempLogFile ¶
func UseTempLogFile(prefix string)
Conveniently Creates a temporary file and sets the Log Handle to a io.writer created for it
Types ¶
type Feedback ¶
type Feedback struct{}
Feedback is special. It writes plainly to the output while logging with the standard extra information (date, file, etc) Only Println and Printf are currently provided for this
type Level ¶
type Level int
Level describes the chosen log level between debug and critical.
const ( LevelTrace Level = iota LevelDebug LevelInfo LevelWarn LevelError LevelCritical LevelFatal DefaultLogThreshold = LevelWarn DefaultStdoutThreshold = LevelError )
func StdoutThreshold ¶
func StdoutThreshold() Level
Level returns the current global output threshold.
Source Files