Emperror: Errors 
Drop-in replacement for the standard library errors package and github.com/pkg/errors.
This is a single, lightweight library merging the features of standard library errors package and github.com/pkg/errors. It also backports a few features (like Go 1.13 error handling related features).
Standard library features:
Newcreates an error with stack traceUnwrapsupports both Go 1.13 wrapper (interface { Unwrap() error }) and pkg/errors causer (interface { Cause() error }) interface- Backported
IsandAsfunctions
github.com/pkg/errors features:
New,Errorf,WithMessage,WithMessagef,WithStack,Wrap,Wrapffunctions behave the same way as in the original libraryCausesupports both Go 1.13 wrapper (interface { Unwrap() error }) and pkg/errors causer (interface { Cause() error }) interface
Additional features:
NewPlaincreates a new error without any attached context, like stack traceSentinelis a shorthand type for creating constant errorWithStackDepthallows attaching stack trace with a custom caller depthWithStackDepthIf,WithStackIf,WrapIf,WrapIffonly annotate errors with a stack trace if there isn't one already in the error chain- Multi error aggregating multiple errors into a single value
NewWithDetails,WithDetailsandWrap*WithDetailsfunctions to add key-value pairs to an error- Match errors using the
matchpackage
Installation
go get emperror.dev/errors
Usage
package main
import "emperror.dev/errors"
// ErrSomethingWentWrong is a sentinel error which can be useful within a single API layer.
const ErrSomethingWentWrong = errors.Sentinel("something went wrong")
// ErrMyError is an error that can be returned from a public API.
type ErrMyError struct {
Msg string
}
func (e ErrMyError) Error() string {
return e.Msg
}
func foo() error {
// Attach stack trace to the sentinel error.
return errors.WithStack(ErrSomethingWentWrong)
}
func bar() error {
return errors.Wrap(ErrMyError{"something went wrong"}, "error")
}
func main() {
if err := foo(); err != nil {
if errors.Cause(err) == ErrSomethingWentWrong { // or errors.Is(ErrSomethingWentWrong)
// handle error
}
}
if err := bar(); err != nil {
if errors.As(err, &ErrMyError{}) {
// handle error
}
}
}
Match errors:
package main
import (
"emperror.dev/errors"
"emperror.dev/errors/match"
)
// ErrSomethingWentWrong is a sentinel error which can be useful within a single API layer.
const ErrSomethingWentWrong = errors.Sentinel("something went wrong")
type clientError interface{
ClientError() bool
}
func foo() error {
// Attach stack trace to the sentinel error.
return errors.WithStack(ErrSomethingWentWrong)
}
func main() {
var ce clientError
matcher := match.Any{match.As(&ce), match.Is(ErrSomethingWentWrong)}
if err := foo(); err != nil {
if matcher.MatchError(err) {
// you can use matchers to write complex conditions for handling (or not) an error
// used in emperror
}
}
}
Development
Contributions are welcome! :)
- Clone the repository
- Make changes on a new branch
- Run the test suite:
./pleasew build ./pleasew test ./pleasew gotest ./pleasew lint - Commit, push and open a PR
License
The MIT License (MIT). Please see License File for more information.
Certain parts of this library are inspired by (or entirely copied from) various third party libraries. Their licenses can be found in the Third Party License File.
