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-rw-r--r--src/fmt/gostringer_example_test.go59
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+// Copyright 2018 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 fmt_test
+
+import (
+ "fmt"
+)
+
+// Address has a City, State and a Country.
+type Address struct {
+ City string
+ State string
+ Country string
+}
+
+// Person has a Name, Age and Address.
+type Person struct {
+ Name string
+ Age uint
+ Addr *Address
+}
+
+// GoString makes Person satisfy the GoStringer interface.
+// The return value is valid Go code that can be used to reproduce the Person struct.
+func (p Person) GoString() string {
+ if p.Addr != nil {
+ return fmt.Sprintf("Person{Name: %q, Age: %d, Addr: &Address{City: %q, State: %q, Country: %q}}", p.Name, int(p.Age), p.Addr.City, p.Addr.State, p.Addr.Country)
+ }
+ return fmt.Sprintf("Person{Name: %q, Age: %d}", p.Name, int(p.Age))
+}
+
+func ExampleGoStringer() {
+ p1 := Person{
+ Name: "Warren",
+ Age: 31,
+ Addr: &Address{
+ City: "Denver",
+ State: "CO",
+ Country: "U.S.A.",
+ },
+ }
+ // If GoString() wasn't implemented, the output of `fmt.Printf("%#v", p1)` would be similar to
+ // Person{Name:"Warren", Age:0x1f, Addr:(*main.Address)(0x10448240)}
+ fmt.Printf("%#v\n", p1)
+
+ p2 := Person{
+ Name: "Theia",
+ Age: 4,
+ }
+ // If GoString() wasn't implemented, the output of `fmt.Printf("%#v", p2)` would be similar to
+ // Person{Name:"Theia", Age:0x4, Addr:(*main.Address)(nil)}
+ fmt.Printf("%#v\n", p2)
+
+ // Output:
+ // Person{Name: "Warren", Age: 31, Addr: &Address{City: "Denver", State: "CO", Country: "U.S.A."}}
+ // Person{Name: "Theia", Age: 4}
+}