业务异常

err := Biz_Call()
if err == TokenExpired {

}

access token expired %f minutes

hasPrefix("access token expired")

// err.ErrorCode == xxxx
if exception.IsTokenExpired(err) {

}

func XXX() error

// 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
}

type wrapError struct {
	msg string
	err error
}

func (e *wrapError) Error() string {
	return e.msg
}

func (e *wrapError) Unwrap() error {
	return e.err
}

type wrapErrors struct {
	msg  string
	errs []error
}

func (e *wrapErrors) Error() string {
	return e.msg
}

func (e *wrapErrors) Unwrap() []error {
	return e.errs
}

func NewAPIException(code int, msg string) *APIException {
	return &APIException{
		code: code,
		msg:  msg,
	}
}

// error的自定义实现
type APIException struct {
	code int
	msg  string
}

func (e *APIException) Error() string {
	return e.msg
}

func (e *APIException) Code() int {
	return e.code
}

// 这个模块定义的业务异常
// token expired %f minitues
// 约定俗成:  ErrXXXXX 来进行自定义异常定义, 方便快速在包里搜索
var (
	ErrAccessTokenExpired  = exception.NewAPIException(5000, "access token expired")
	ErrRefreshTokenExpired = exception.NewAPIException(5001, "refresh token expired")
)

if aDelta > 0 {
    return ErrAccessTokenExpired.WithMessagef("access token expired %f minutes", aDelta)
}

if e, ok := err.(*exception.APIException); ok {
    t.Log(e.String())
    // 判断该异常是不是 TokenExpired异常
    if e.Code == token.ErrAccessTokenExpired.Code {
        t.Log(e.String())
    }
}

// 	 exception.IsException(err, token.ErrAccessTokenExpired)
// 给一个异常判断的方法
func IsException(err error, e *APIException) bool {
	if targe, ok := err.(*APIException); ok {
		return targe.Code == e.Code
	}

	return false
}