errors
Just another error handling primitives for golang
Install
go install github.com/WAY29/errors@latest
Usage
New error and print error context
The errors.New()/errors.Newf() function returns a new error that has a context, and you can use "%+v" as format descriptor to print error context. For example
err := errors.New("an_error")
fmt.Printf("%+v", err) // will print error message and context information
Print error message
err := errors.New("an_error")
fmt.Printf("%+v", err) // will print error message and context information
fmt.Printf("%#v", err) // will only print error context information
fmt.Printf("%v", err) // will only print error message
fmt.Printf("%s", err) // will only print error message
Adding context to an error
The errors.Wrap()/errors.Wrapf() function returns a new error that adds context to the original error. For example
_, err := ioutil.ReadAll(r)
if err != nil {
return errors.Wrap(err, "read failed")
}
Adding error type to an error
The errors.SetType() function returns a new error that adds error type to wrapped error. For example
type ErrorType uint16
const (
RequestError ErrorType = iota
ResponseError
)
func test() {
err := errors.New("new error")
err, _ = errors.SetType(err, RequestError)
// or errors.SetTypeWithoutBool
// err = errors.SetTypeWithoutBool(err, RequestError)
switch errType := errors.GetType(err); errType {
case RequestError:
fmt.Printf("Request error: %+v\n", err)
case ResponseError:
fmt.Printf("Response error: %+v\n", err)
default:
fmt.Printf("Unknown error: %#v\n", err)
}
}
Adding more information to an error
The errors.Wrap()/errors.Wrapf() function can also be used to add additional information to wrapped errors. For example
err := errors.New("an_error")
err = errors.Wrap(err, "more information")
fmt.Printf("%+v", err) // will print error message and context information
Retrieving the cause of an error
Using errors.Wrap() constructs a stack of errors, adding context to the preceding error. Depending on the nature of the error it may be necessary to reverse the operation of errors.Wrap to retrieve the original error for inspection. Any error value which implements this interface can be inspected by errors.Cause.
type causer interface {
Cause() error
}
errors.Cause will recursively retrieve the topmost error which does not implement causer, which is assumed to be the original cause. For example:
switch err := errors.Cause(err).(type) {
case *MyError:
// handle specifically
default:
// unknown error
}
How I use this library
For example
package errors
import (
"fmt"
"github.com/WAY29/errors"
)
type ErrorType uint16
const (
RequestError ErrorType = iota
ResponseError
)
func main() {
// errors.SetCurrentAbsPath()
err := errors.New("new error")
err, _ = errors.SetType(err, RequestError)
err = errors.Wrapf(err, "wrapped")
switch errType := errors.GetType(err); errType {
case RequestError:
fmt.Printf("Request error: %+v\n", err)
case ResponseError:
fmt.Printf("Response error: %+v\n", err)
default:
fmt.Printf("Unknown error: %#v\n", err)
}
}
Benchmark
BenchmarkError1000
BenchmarkError1000-16
2483836 461.6 ns/op 48 B/op 2 allocs/op
BenchmarkError10000
BenchmarkError10000-16
2560116 459.6 ns/op 48 B/op 2 allocs/op
BenchmarkWrappedError1000
BenchmarkWrappedError1000-16
933684 1283 ns/op 360 B/op 11 allocs/op
BenchmarkWrappedError10000
BenchmarkWrappedError10000-16
958335 1263 ns/op 360 B/op 11 allocs/op
Notice
- If you run golang files by
go run, please runerrors.SetCurrentAbsPath()first, or stack message about path will be absolute path. - If you want to skip some frame about stack, please run
errors.SetSkipFrameNum(skipNum), this is usually used for your secondary encapsulation of the library.
