errcode

A simple codegen module for generating unique, stable error codes as function identifiers, making errors easily traceable.

download the package

go get github.com/calvinsomething/errcode

run errcode

Add //go:generate go run github.com/calvinsomething/errcode to any Go file in your project, then run go generate from the project root. The first time the program runs, it will add an errcode package to your project.

use error codes

Use errcode.New in your code to construct an errcode.Error. Running go generate now will replace any instance of New with an equivalent function with an error code as an identifier, and an Error.Code value equal to the same error code used as the function name.

	return errcode.New("Invalid image format.")

becomes:

	return errcode.K9S6O("Invalid image format.")

The functions will be declared in the generated errcode package.

// K9S6O returns an Error constructed by NewErrorFunc.
func K9S6O(m string, fa ...interface{}) Error {
	return NewErrorFunc("K9S6O", m, fa...)
}

add a prefix

Append --prefix <prefix> to the run command to add a prefix to any new error code generated; helpful for differentiating between error code sources.

reassignable implementations

NewErrorFunc, ErrorStringFunc, and WrapFunc can be assigned for customizing the behavior of New, Error.Error and Error.Wrap, respectively.

You can reassign these variables from outside of the generated errcode package, or you can add a file within the package for access to private members.

Example:

package errcode

import (
	"fmt"
	"runtime"
)

func myWrapFunc(e Error, w error) {
	_, file, line, ok := runtime.Caller(2)
	if !ok {
		file = "'unknown file'"
		line = -1
	}

	e.p.wrapped = fmt.Errorf("%s:%d: %w", file, line, w)
}

func init() {
	WrapFunc = myWrapFunc
}