update book code

eBook/examples/chapter_12/gob1.go

@@ -0,0 +1,41 @@
+// gob1.go
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"encoding/gob"
+	"log"
+)
+
+type P struct {
+	X, Y, Z int
+	Name    string
+}
+
+type Q struct {
+	X, Y *int32
+	Name string
+}
+
+func main() {
+	// Initialize the encoder and decoder.  Normally enc and dec would be      
+	// bound to network connections and the encoder and decoder would      
+	// run in different processes.      
+	var network bytes.Buffer   // Stand-in for a network connection      
+	enc := gob.NewEncoder(&network) // Will write to network.      
+	dec := gob.NewDecoder(&network)	// Will read from network.      
+	// Encode (send) the value.      
+	err := enc.Encode(P{3, 4, 5, "Pythagoras"})
+	if err != nil {
+		log.Fatal("encode error:", err)
+	}
+	// Decode (receive) the value.      
+	var q Q
+	err = dec.Decode(&q)
+	if err != nil {
+		log.Fatal("decode error:", err)
+	}
+	fmt.Printf("%q: {%d,%d}\n", q.Name, *q.X, *q.Y)
+}
+// Output:   "Pythagoras": {3,4}