update book code

eBook/examples/chapter_10/pointer_value.go

@@ -0,0 +1,28 @@
+// pointer_value.go
+package main
+
+import (
+	"fmt"
+)
+
+type B struct {
+	thing  int
+}
+
+func (b *B) change() {  b.thing = 1 }
+
+func (b B) write() string { return fmt.Sprint(b) }
+
+func main() {
+	  var b1 B  // b1 is value
+      b1.change()
+      fmt.Println(b1.write())
+
+      b2 := new(B)  // b2 is pointer
+      b2.change()
+      fmt.Println(b2.write())
+}
+/* Output:
+{1}
+{1}
+*/