Multierror.go, mutliple go error container.

multierror.go

// MultiError don't use directly, use NewMultiError
type MultiError map[string]error

// NewMultiError returns nil if all errs are nil
func NewMultiError(errs map[string]error) error {
	for k, v := range errs {
		if v == nil {
			delete(errs, k)
		}
	}

	if len(errs) == 0 {
		return nil
	}
	return MultiError(errs)
}

func (m MultiError) Error() string {
	var errStrs []string
	for k, v := range m {
		errStrs = append(errStrs, fmt.Sprintf("%s: %s", k, v.Error()))
	}
	if len(errStrs) == 0 {
		panic("multi error used without errors")
	}
	return strings.Join(errStrs, ".\n")
}