// Copyright 2011 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.
|
|
// This file contains the code snippets included in "Error Handling and Go."
|
|
package main
|
|
import (
|
"encoding/json"
|
"errors"
|
"fmt"
|
"log"
|
"net"
|
"os"
|
"time"
|
)
|
|
type File struct{}
|
|
func Open(name string) (file *File, err error) {
|
// OMIT
|
panic(1)
|
// STOP OMIT
|
}
|
|
func openFile() { // OMIT
|
f, err := os.Open("filename.ext")
|
if err != nil {
|
log.Fatal(err)
|
}
|
// do something with the open *File f
|
// STOP OMIT
|
_ = f
|
}
|
|
// errorString is a trivial implementation of error.
|
type errorString struct {
|
s string
|
}
|
|
func (e *errorString) Error() string {
|
return e.s
|
}
|
|
// STOP OMIT
|
|
// New returns an error that formats as the given text.
|
func New(text string) error {
|
return &errorString{text}
|
}
|
|
// STOP OMIT
|
|
func Sqrt(f float64) (float64, error) {
|
if f < 0 {
|
return 0, errors.New("math: square root of negative number")
|
}
|
// implementation
|
return 0, nil // OMIT
|
}
|
|
// STOP OMIT
|
|
func printErr() (int, error) { // OMIT
|
f, err := Sqrt(-1)
|
if err != nil {
|
fmt.Println(err)
|
}
|
// STOP OMIT
|
// fmtError OMIT
|
if f < 0 {
|
return 0, fmt.Errorf("math: square root of negative number %g", f)
|
}
|
// STOP OMIT
|
return 0, nil
|
}
|
|
type NegativeSqrtError float64
|
|
func (f NegativeSqrtError) Error() string {
|
return fmt.Sprintf("math: square root of negative number %g", float64(f))
|
}
|
|
// STOP OMIT
|
|
type SyntaxError struct {
|
msg string // description of error
|
Offset int64 // error occurred after reading Offset bytes
|
}
|
|
func (e *SyntaxError) Error() string { return e.msg }
|
|
// STOP OMIT
|
|
func decodeError(dec *json.Decoder, val struct{}) error { // OMIT
|
var f os.FileInfo // OMIT
|
if err := dec.Decode(&val); err != nil {
|
if serr, ok := err.(*json.SyntaxError); ok {
|
line, col := findLine(f, serr.Offset)
|
return fmt.Errorf("%s:%d:%d: %v", f.Name(), line, col, err)
|
}
|
return err
|
}
|
// STOP OMIT
|
return nil
|
}
|
|
func findLine(os.FileInfo, int64) (int, int) {
|
// place holder; no need to run
|
return 0, 0
|
}
|
|
func netError(err error) { // OMIT
|
for { // OMIT
|
if nerr, ok := err.(net.Error); ok && nerr.Temporary() {
|
time.Sleep(1e9)
|
continue
|
}
|
if err != nil {
|
log.Fatal(err)
|
}
|
// STOP OMIT
|
}
|
}
|
|
func main() {}
|
