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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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