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Source file src/encoding/gob/example_encdec_test.go

Documentation: encoding/gob

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

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