README
¶
Errlog: reduce debugging time while programming 
Introduction
Use errlog to improve error logging and speed up debugging while you create amazing code :
- Highlight source code
- Detect and point out which func call is causing the fail
- Pretty stack trace
- No-op mode for production
- Easy implementation, adaptable logger
- Plug to any current project without changing you or your teammates habits
- Plug to your current logging system
| Go to |
|---|
| Get started |
| Documentation |
| Examples |
| Tweaking |
| Feedbacks |
| Contributions |
| License |
| Contributors |
Get started
Install
go get github.com/snwfdhmp/errlog
Usage
Replace your if err != nil with if errlog.Debug(err) to add debugging informations.
func someFunc() {
//...
if errlog.Debug(err) { // will debug & pass if err != nil, will ignore if err == nil
return
}
}
In production, call errlog.DefaultLogger.Disable(true) to enable no-op (equivalent to if err != nil)
Tweak as you need
You can configure your own logger with the following options :
type Config struct {
PrintFunc func(format string, data ...interface{}) //Printer func (eg: fmt.Printf)
LinesBefore int //How many lines to print *before* the error line when printing source code
LinesAfter int //How many lines to print *after* the error line when printing source code
PrintStack bool //Shall we print stack trace ? yes/no
PrintSource bool //Shall we print source code along ? yes/no
PrintError bool //Shall we print the error of Debug(err) ? yes/no
ExitOnDebugSuccess bool //Shall we os.Exit(1) after Debug has finished logging everything ? (doesn't happen when err is nil). Will soon be replaced by ExitFunc to enable panic-ing the current goroutine. (if you need this quick, please open an issue)
}
As we don't yet update automatically this README immediately when we add new features, this definition may be outdated. (Last update: 2019/08/07) See the struct definition in godoc.org for the up to date definition
Example
Try yourself
| Name and link | Description |
|---|---|
| Basic | standard usage, quick setup |
| Custom | guided configuration for fulfilling your needs |
| Disabled | how to disable the logging & debugging (eg: for production use) |
| Failing line far away | example of finding the func call that caused the error while it is lines away from the errlog.Debug call |
| Pretty stack trace | pretty stack trace printing instead of debugging. |
Just read
Basic example
Note that in the example, you will see some unuseful func. Those are made to generate additional stack trace levels for the sake of example
We're going to use this sample program :
func main() {
fmt.Println("Program start")
wrapingFunc() //call to our important function
fmt.Println("Program end")
}
func wrapingFunc() {
someBigFunction() // call some func
}
func someBigFunction() {
someDumbFunction() // just random calls
someSmallFunction() // just random calls
someDumbFunction() // just random calls
// Here it can fail, so instead of `if err != nil` we use `errlog.Debug(err)`
if err := someNastyFunction(); errlog.Debug(err) {
return
}
someSmallFunction() // just random calls
someDumbFunction() // just random calls
}
func someSmallFunction() {
_ = fmt.Sprintf("I do things !")
}
func someNastyFunction() error {
return errors.New("I'm failing for some reason") // simulate an error
}
func someDumbFunction() bool {
return false // just random things
}
Output
We are able to detect and point out which line is causing the error.
Custom Configuration Example
Let's see what we can do with a custom configuration.
debug := errlog.NewLogger(&errlog.Config{
// PrintFunc is of type `func (format string, data ...interface{})`
// so you can easily implement your own logger func.
// In this example, logrus is used, but any other logger can be used.
// Beware that you should add '\n' at the end of format string when printing.
PrintFunc: logrus.Printf,
PrintSource: true, //Print the failing source code
LinesBefore: 2, //Print 2 lines before failing line
LinesAfter: 1, //Print 1 line after failing line
PrintError: true, //Print the error
PrintStack: false, //Don't print the stack trace
ExitOnDebugSuccess: true, //Exit if err
})
Please note: This definition may be outdated. (Last update: 2019/08/07) See the struct definition in godoc.org for the up to date definition
Output
When the failing func call is a few lines away
Even when the func call is a few lines away, there is no problem for finding it.
Output
Documentation
Documentation can be found here :
Feedbacks
Feel free to open an issue for any feedback or suggestion.
I fix process issues quickly.
Contributions
We are happy to collaborate with you :
- Ask for a new feature: Open an issue
- Add your feature: Open a PR
When submitting a PR, please apply Effective Go best practices. For more information: https://golang.org/doc/effective_go.html
License information
Click the following badge to open LICENSE information.
Contributors
Major
Minor fixes
Documentation
¶
Overview ¶
Package errlog provides a simple object to enhance Go source code debugging
Example result:
$ go run myfailingapp.go
Program starting
error in main.main: something failed here
line 13 of /Users/snwfdhmp/go/src/github.com/snwfdhmp/sandbox/testerr.go
9: func main() {
10: fmt.Println("Program starting")
11: err := errors.New("something failed here")
12:
13: errlog.Debug(err)
14:
15: fmt.Println("End of the program")
16: }
exit status 1
You can configure your own logger with these options :
type Config struct {
LinesBefore int
LinesAfter int
PrintStack bool
PrintSource bool
PrintError bool
ExitOnDebugSuccess bool
}
Example :
debug := errlog.NewLogger(&errlog.Config{
LinesBefore: 2,
LinesAfter: 1,
PrintError: true,
PrintSource: true,
PrintStack: false,
ExitOnDebugSuccess: true,
})
// ...
if err != nil {
debug.Debug(err)
return
}
Outputs :
Error in main.someBigFunction(): I'm failing for no reason
line 41 of /Users/snwfdhmp/go/src/github.com/snwfdhmp/sandbox/testerr.go:41
33: func someBigFunction() {
...
40: if err := someNastyFunction(); err != nil {
41: debug.Debug(err)
42: return
43: }
exit status 1
Index ¶
Constants ¶
const ( // ModeDisabled represents the disabled mode (NO-OP) ModeDisabled = iota + 1 // ModeEnabled represents the enabled mode (Print) ModeEnabled )
Variables ¶
var ( //DefaultLoggerPrintFunc is fmt.Printf without return values DefaultLoggerPrintFunc = func(format string, data ...interface{}) { fmt.Printf(format+"\n", data...) } //DefaultLogger logger implements default configuration for a logger DefaultLogger = &logger{ config: &Config{ PrintFunc: DefaultLoggerPrintFunc, LinesBefore: 4, LinesAfter: 2, PrintStack: false, PrintSource: true, PrintError: true, ExitOnDebugSuccess: false, }, } )
Functions ¶
func PrintStackMinus ¶
func PrintStackMinus(depthToRemove int)
PrintStackMinus prints the current stack trace minus the amount of depth in parameter
func SetDebugMode ¶
func SetDebugMode(toggle bool)
SetDebugMode sets debug mode to On if toggle==true or Off if toggle==false. It changes log level an so displays more logs about whats happening. Useful for debugging.
Types ¶
type Config ¶
type Config struct {
PrintFunc func(format string, data ...interface{}) //Printer func (eg: fmt.Printf)
LinesBefore int //How many lines to print *before* the error line when printing source code
LinesAfter int //How many lines to print *after* the error line when printing source code
PrintStack bool //Shall we print stack trace ? yes/no
PrintSource bool //Shall we print source code along ? yes/no
PrintError bool //Shall we print the error of Debug(err) ? yes/no
ExitOnDebugSuccess bool //Shall we os.Exit(1) after Debug has finished logging everything ? (doesn't happen when err is nil)
DisableStackIndentation bool //Shall we print stack vertically instead of indented
Mode int
}
Config holds the configuration for a logger
type Logger ¶
type Logger interface {
// Debug wraps up Logger debugging funcs related to an error
// If the given error is nil, it returns immediately
// It relies on Logger.Config to determine what will be printed or executed
// It returns whether err != nil
Debug(err error) bool
//PrintSource prints lines based on given opts (see PrintSourceOptions type definition)
PrintSource(lines []string, opts PrintSourceOptions)
//DebugSource debugs a source file
DebugSource(filename string, lineNumber int)
//SetConfig replaces current config with the given one
SetConfig(cfg *Config)
//Config returns current config
Config() *Config
//Disable is used to disable Logger (every call to this Logger will perform NO-OP (no operation)) and return instantly
//Use Disable(true) to disable and Disable(false) to enable again
Disable(bool)
}
Logger interface allows to log an error, or to print source code lines. Check out NewLogger function to learn more about Logger objects and Config.
type PrintSourceOptions ¶
type PrintSourceOptions struct {
FuncLine int
StartLine int
EndLine int
Highlighted map[int][]int //map[lineIndex][columnstart, columnEnd] of chars to highlight
}
PrintSourceOptions represents config for (*logger).PrintSource func
type StackTraceItem ¶
type StackTraceItem struct {
CallingObject string
Args []string
SourcePathRef string
SourceLineRef int
MysteryNumber int64 // don't know what this is, no documentation found, if you know please let me know via a PR !
}
StackTraceItem represents parsed information of a stack trace item
Source Files
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