error

基础构造

// The error built-in interface type is the conventional interface for representing an error condition, with the nil value representing no error.
type error interface {
	Error() string
}

// New returns an error that formats as the given text. Each call to New returns a distinct error value even if the text is identical.
func New(text string) error {
	return &errorString{text}
}

// errorString is a trivial implementation of error.
type errorString struct {
	s string
}

func (e *errorString) Error() string {
	return e.s
}

规范：errors.New("packageName： error info ")

errors.New()返回的是一个地址，因为如果直接返回结构体，如果两个error的内容相同，可能==会是ture