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Overview

errorc​

errorc is a minimalistic extension to Go's standard error type, providing additional structured context.

Usage​

Compared to fmt.Errorf​

The errorc.With function behaves like fmt.Errorf, but performs significantly faster in benchmarks:

BenchmarkWith-8         53965288                21.81 ns/op
BenchmarkFmtErrorf-8     7401583               186.7 ns/op

Sentinel errors​

The With function allows wrapping a sentinel error with additional context and later identifying this error using errors.Is.

package main

import (
	"errors"
	"fmt"
	
	"github.com/ygrebnov/errorc"
)

func main() {
	// Create a new named error.
	ErrInvalidInput := errorc.New("invalid input")

	// Wrap the named error with additional context.
	err := errorc.With(
		ErrInvalidInput,
		errorc.Field("field1", "value1"),
		errorc.Field("field2", "value2"),
	)

	// Identify the error using errors.Is.
	if errors.Is(err, ErrInvalidInput) {
		// Handle the invalid input error.
		fmt.Print("Handled invalid input error: ", err.Error())
	}

	// Output: Handled invalid input error: invalid input, field1: value1, field2: value2
}

Typed errors​

The With function allows wrapping a typed error with additional context and later identifying this error using errors.As.

package main

import (
	"errors"
	"fmt"
	
	"github.com/ygrebnov/errorc"
)

type ValidationError struct {
	Message string
}

func (e *ValidationError) Error() string {
	return e.Message
}

func main() {
	// Create a new error of type ValidationError.
	err := errorc.With(
		&ValidationError{"invalid input"},
		errorc.Field("field1", "value1"),
		errorc.Field("field2", "value2"),
	)

	// Identify ValidationError using errors.As.
	var ve *ValidationError
	if errors.As(err, &ve) {
		// Handle ValidationError.
		fmt.Print("Handled ValidationError: ", err.Error())
	}

	// Output: Handled ValidationError: invalid input, field1: value1, field2: value2
}

Additional Resources​