mirror of https://github.com/golang/go.git
62 lines
1.5 KiB
Go
62 lines
1.5 KiB
Go
// Copyright 2013 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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package gob_test
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import (
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"bytes"
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"encoding/gob"
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"fmt"
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"log"
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)
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// The Vector type has unexported fields, which the package cannot access.
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// We therefore write a BinaryMarshal/BinaryUnmarshal method pair to allow us
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// to send and receive the type with the gob package. These interfaces are
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// defined in the "encoding" package.
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// We could equivalently use the locally defined GobEncode/GobDecoder
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// interfaces.
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type Vector struct {
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x, y, z int
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}
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func (v Vector) MarshalBinary() ([]byte, error) {
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// A simple encoding: plain text.
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var b bytes.Buffer
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fmt.Fprintln(&b, v.x, v.y, v.z)
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return b.Bytes(), nil
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}
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// UnmarshalBinary modifies the receiver so it must take a pointer receiver.
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func (v *Vector) UnmarshalBinary(data []byte) error {
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// A simple encoding: plain text.
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b := bytes.NewBuffer(data)
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_, err := fmt.Fscanln(b, &v.x, &v.y, &v.z)
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return err
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}
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// This example transmits a value that implements the custom encoding and decoding methods.
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func Example_encodeDecode() {
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var network bytes.Buffer // Stand-in for the network.
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// Create an encoder and send a value.
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enc := gob.NewEncoder(&network)
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err := enc.Encode(Vector{3, 4, 5})
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if err != nil {
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log.Fatal("encode:", err)
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}
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// Create a decoder and receive a value.
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dec := gob.NewDecoder(&network)
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var v Vector
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err = dec.Decode(&v)
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if err != nil {
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log.Fatal("decode:", err)
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}
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fmt.Println(v)
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// Output:
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// {3 4 5}
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}
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