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Originally published on The Go Programming Language Blog, July 12, 2011. http://blog.golang.org/2011/07/error-handling-and-go.html Update #2547 R=golang-dev, r CC=golang-dev https://golang.org/cl/5475060
116 lines
2.2 KiB
Go
116 lines
2.2 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This file contains the code snippets included in "Error Handling and Go."
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package main
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import (
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"encoding/json"
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"errors"
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"fmt"
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"log"
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"net"
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"os"
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"time"
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)
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type File struct{}
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func Open(name string) (file *File, err error)
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func openFile() { // OMIT
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f, err := os.Open("filename.ext")
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if err != nil {
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log.Fatal(err)
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}
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// do something with the open *File f
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// STOP OMIT
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_ = f
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}
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// errorString is a trivial implementation of error.
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type errorString struct {
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s string
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}
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func (e *errorString) Error() string {
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return e.s
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}
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// STOP OMIT
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// New returns an error that formats as the given text.
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func New(text string) error {
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return &errorString{text}
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}
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// STOP OMIT
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func Sqrt(f float64) (float64, error) {
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if f < 0 {
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return 0, errors.New("math: square root of negative number")
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}
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// implementation
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return 0, nil // OMIT
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}
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// STOP OMIT
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func printErr() (int, error) { // OMIT
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f, err := Sqrt(-1)
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if err != nil {
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fmt.Println(err)
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}
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// STOP OMIT
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// fmtError OMIT
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if f < 0 {
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return 0, fmt.Errorf("math: square root of negative number %g", f)
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}
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// STOP OMIT
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return 0, nil
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}
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type NegativeSqrtError float64
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func (f NegativeSqrtError) Error() string {
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return fmt.Sprintf("math: square root of negative number %g", float64(f))
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}
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// STOP OMIT
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type SyntaxError struct {
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msg string // description of error
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Offset int64 // error occurred after reading Offset bytes
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}
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func (e *SyntaxError) Error() string { return e.msg }
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// STOP OMIT
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func decodeError(dec *json.Decoder, val struct{}) error { // OMIT
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var f os.FileInfo // OMIT
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if err := dec.Decode(&val); err != nil {
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if serr, ok := err.(*json.SyntaxError); ok {
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line, col := findLine(f, serr.Offset)
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return fmt.Errorf("%s:%d:%d: %v", f.Name(), line, col, err)
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}
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return err
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}
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// STOP OMIT
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return nil
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}
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func findLine(os.FileInfo, int64) (int, int)
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func netError(err error) { // OMIT
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for { // OMIT
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if nerr, ok := err.(net.Error); ok && nerr.Temporary() {
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time.Sleep(1e9)
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continue
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}
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if err != nil {
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log.Fatal(err)
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}
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// STOP OMIT
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}
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}
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func main() {}
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