From b521ff421ea09ad3d7440fdc84562d6fca2d4b46 Mon Sep 17 00:00:00 2001
From: Nattawit Chaiworawitsakul <c.nattawit@gmail.com>
Date: Sat, 17 Jun 2017 11:30:34 +0700
Subject: [PATCH] #75 Wrap() add withStack only if no cause with stack present
---
errors.go | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/errors.go b/errors.go
index 842ee80..8c6664e 100644
--- a/errors.go
+++ b/errors.go
@@ -121,6 +121,8 @@ type fundamental struct {
*stack
}
+func (f *fundamental) hasStack() bool { return true }
+
func (f *fundamental) Error() string { return f.msg }
func (f *fundamental) Format(s fmt.State, verb rune) {
@@ -174,13 +176,24 @@ func (w *withStack) Format(s fmt.State, verb rune) {
}
}
+func (w *withStack) hasStack() bool { return true }
+
// Wrap returns an error annotating err with a stack trace
// at the point Wrap is called, and the supplied message.
// If err is nil, Wrap returns nil.
func Wrap(err error, message string) error {
+ type hasStacker interface {
+ hasStack() bool
+ }
if err == nil {
return nil
}
+ if stacker, ok := err.(hasStacker); ok && stacker.hasStack() {
+ return &withMessage{
+ cause: err,
+ msg: message,
+ }
+ }
err = &withMessage{
cause: err,
msg: message,
@@ -195,9 +208,18 @@ func Wrap(err error, message string) error {
// at the point Wrapf is call, and the format specifier.
// If err is nil, Wrapf returns nil.
func Wrapf(err error, format string, args ...interface{}) error {
+ type hasStacker interface {
+ hasStack() bool
+ }
if err == nil {
return nil
}
+ if stacker, ok := err.(hasStacker); ok && stacker.hasStack() {
+ return &withMessage{
+ cause: err,
+ msg: fmt.Sprintf(format, args...),
+ }
+ }
err = &withMessage{
cause: err,
msg: fmt.Sprintf(format, args...),
@@ -242,6 +264,16 @@ func (w *withMessage) Format(s fmt.State, verb rune) {
}
}
+func (w *withMessage) hasStack() bool {
+ type hasStacker interface {
+ hasStack() bool
+ }
+ if cause, ok := w.Cause().(hasStacker); ok {
+ return cause.hasStack()
+ }
+ return false
+}
+
// Cause returns the underlying cause of the error, if possible.
// An error value has a cause if it implements the following
// interface: