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- // 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() {}
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