typed_errors

README

go-typed-errors

Why this repo was created?

Main reason was to create additional methods for better error typing support.

Features

• Errors as constants
• errors.Is support
• xerrors.Wrapper support with Unwrap method
• String.NewWithArgs support to add context arguments for error message, while errors.Is working
• String.NewWithStack support to store stack trace (untested)
• IDE highlighting, as type based on strings

Show me the code

https://play.golang.org/p/ZSHBCxXQx6A

package main

import (
	"errors"
	typedErrors "github.com/Bogdan-D/go-typed-errors"
	"log"
)

const ErrWrongBehaviour = typedErrors.String("wrong behaviour: %v")

func someFunc() error {
	return errors.New("someFunc failed")
}

func typedError(args ...interface{}) error {
	err := someFunc()
	if err != nil {
		return ErrWrongBehaviour.NewWithArgs(args...).Wrap(err)
	}
	return nil
}

func main() {
	err := typedError("not typed errors")

	// handle ErrWrongBehaviour error type
	if errors.Is(err, ErrWrongBehaviour) {
		log.Print("typedError handled: ", err)
	} else if err != nil {
		log.Print("other error cases:", err)
	}
}

Benchmark

Comparsion Wrap with Errorf for wrapping errors

goos: linux
goarch: amd64
pkg: github.com/Bogdan-D/go-typed-errors
cpu: Intel(R) Core(TM) i7-1065G7 CPU @ 1.30GHz
BenchmarkWrap-8                  7856391               180.7 ns/op            88 B/op          5 allocs/op
BenchmarkErrorfWrap-8            4080972               291.3 ns/op            64 B/op          3 allocs/op

Documentation

Index

• func Stack(err error) string
• func Wrap(err, cause error) (e wrapped)
• func WrapWithStack(err, cause error) wrapped
• type ErrorString
• type String
  • func (e String) Error() string
  • func (e String) New() typedError
  • func (e String) NewWithArgs(args ...interface{}) formattedError
  • func (e String) String() string
• type TypedError
• type Wrapped

Functions

func Stack

func Stack(err error) string

Stack returns stack if err is wrapped or implements Stack() string method

func Wrap

func Wrap(err, cause error) (e wrapped)

Wrap wraps an error, adds its cause and stack trace

func WrapWithStack

func WrapWithStack(err, cause error) wrapped

WrapWithStack wraps cause with err and stores stack trace

Types

type ErrorString

type ErrorString = String

type String

type String string

String which used in const as error

func (String) Error

func (e String) Error() string

Error implements errors interface

func (String) New

func (e String) New() typedError

New returns new typed error

func (String) NewWithArgs

func (e String) NewWithArgs(args ...interface{}) formattedError

NewWithArgs returns new error which would be formattedError Note: if two errors has different arguments they still would be equal Used Sprintf for formatting, so use #Wrap method instead of %w for wrapping

func (String) String

func (e String) String() string

typedError implements stringer interface

type TypedError

type TypedError interface {
	error

	Is(err error) bool        // Is checks if TypedError and provided error has same type
	Wrap(cause error) wrapped // Wrap wraps provided error
	WithStack() wrapped       // Stack stores call stack and returns wrapped error
}

type Wrapped

type Wrapped interface {
	Unwrap() error
}