Custom printing of Go structs with Stringer interface

printf.go

package main

import (
	"fmt"

	"github.com/hashicorp/go-hclog"
)

type Cage struct {
	Bo Bottle
	Pa Pack
}

func (cage Cage) String() string {
	return fmt.Sprintf("Bo:\n%v\nPa:\n%v\n", cage.Bo, cage.Pa)
}

type Bottle struct {
	Volume   int
	Contents string
}

func (btl Bottle) String() string {
	return fmt.Sprintf("Volume:   %v\nContents: %v\n", btl.Volume, btl.Contents)
}

type Pack struct {
	Material string
	Liquid   string
}

func (pac Pack) String() string {
	return fmt.Sprintf("Material: %v\nLiquid:   %v\n", pac.Material, pac.Liquid)
}

func main() {
	log := hclog.New(&hclog.LoggerOptions{DisableTime: true})

	cage := Cage{
		Bo: Bottle{
			Volume:   33,
			Contents: "IPA",
		},
		Pa: Pack{
			Material: "cardboard",
			Liquid:   "milk",
		},
	}

	fmt.Println("1 Println")
	fmt.Println(cage)

	fmt.Printf("2 %%v\n%v\n", cage)

	fmt.Printf("3 %%+v\n%+v\n", cage)

	log.Info("parsed input together", "cage", cage)

	log.Info("parsed input separated", "cage.Bottle", cage.Bo, "cage.Pack", cage.Pa)

}

// 1 Println
// Bo:
// Volume:   33
// Contents: IPA
//
// Pa:
// Material: cardboard
// Liquid:   milk
//
//
// 2 %v
// Bo:
// Volume:   33
// Contents: IPA
//
// Pa:
// Material: cardboard
// Liquid:   milk
//
//
// 3 %+v
// Bo:
// Volume:   33
// Contents: IPA
//
// Pa:
// Material: cardboard
// Liquid:   milk
//
//
// [INFO]  parsed input together:
//  cage=
//  | Bo:
//  | Volume:   33
//  | Contents: IPA
//  | 
//  | Pa:
//  | Material: cardboard
//  | Liquid:   milk
//  | 
//  
// [INFO]  parsed input separated:
//  cage.Bottle=
//  | Volume:   33
//  | Contents: IPA
//  
//  cage.Pack=
//  | Material: cardboard
//  | Liquid:   milk

Can be easily extended to redact sensitive fields.