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// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package errors_test
import (
"errors"
"fmt"
"os"
"time"
)
// MyError2 is an error implementation that includes a time, a message, and an
// underlying error.
type MyError2 struct {
When time.Time
What string
err error
}
func (e MyError2) Error() string {
return fmt.Sprintf("%v at %v: %v", e.What, e.When, e.err)
}
// Unwrap returns e's underlying error, or nil if there is none.
func (e MyError2) Unwrap() error {
return e.err
}
func readConfig() error {
if _, err := os.Open("non-existing"); err != nil {
return MyError2{
time.Date(1989, 3, 15, 22, 30, 0, 0, time.UTC),
"reading config file",
err,
}
}
return nil
}
func Example_unwrap() {
if err := readConfig(); err != nil {
// Display the error.
fmt.Println(err)
// If we can retrieve the path, try to recover
// by taking another action.
var pe *os.PathError
if errors.As(err, &pe) {
restoreFile(pe.Path)
}
}
// Output: reading config file at 1989-03-15 22:30:00 +0000 UTC: open non-existing: no such file or directory
}
func restoreFile(path string) {}
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