gostringer_example_test.go

Documentation: fmt

		 1  // Copyright 2018 The Go Authors. All rights reserved.
		 2  // Use of this source code is governed by a BSD-style
		 3  // license that can be found in the LICENSE file.
		 4  
		 5  package fmt_test
		 6  
		 7  import (
		 8  	"fmt"
		 9  )
		10  
		11  // Address has a City, State and a Country.
		12  type Address struct {
		13  	City		string
		14  	State	 string
		15  	Country string
		16  }
		17  
		18  // Person has a Name, Age and Address.
		19  type Person struct {
		20  	Name string
		21  	Age	uint
		22  	Addr *Address
		23  }
		24  
		25  // GoString makes Person satisfy the GoStringer interface.
		26  // The return value is valid Go code that can be used to reproduce the Person struct.
		27  func (p Person) GoString() string {
		28  	if p.Addr != nil {
		29  		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)
		30  	}
		31  	return fmt.Sprintf("Person{Name: %q, Age: %d}", p.Name, int(p.Age))
		32  }
		33  
		34  func ExampleGoStringer() {
		35  	p1 := Person{
		36  		Name: "Warren",
		37  		Age:	31,
		38  		Addr: &Address{
		39  			City:		"Denver",
		40  			State:	 "CO",
		41  			Country: "U.S.A.",
		42  		},
		43  	}
		44  	// If GoString() wasn't implemented, the output of `fmt.Printf("%#v", p1)` would be similar to
		45  	// Person{Name:"Warren", Age:0x1f, Addr:(*main.Address)(0x10448240)}
		46  	fmt.Printf("%#v\n", p1)
		47  
		48  	p2 := Person{
		49  		Name: "Theia",
		50  		Age:	4,
		51  	}
		52  	// If GoString() wasn't implemented, the output of `fmt.Printf("%#v", p2)` would be similar to
		53  	// Person{Name:"Theia", Age:0x4, Addr:(*main.Address)(nil)}
		54  	fmt.Printf("%#v\n", p2)
		55  
		56  	// Output:
		57  	// Person{Name: "Warren", Age: 31, Addr: &Address{City: "Denver", State: "CO", Country: "U.S.A."}}
		58  	// Person{Name: "Theia", Age: 4}
		59  }
		60
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