// Chapter 29 example: fmt.Stringer, an interface from the standard library.
// Run with: go run exercises/29/05-stringer.go

package main

import "fmt"

type point struct {
	x int
	y int
}

func (p point) String() string {
	return fmt.Sprintf("(%d, %d)", p.x, p.y)
}

type size struct {
	w int
	h int
}

func main() {
	p := point{x: 3, y: 4}
	fmt.Println(p)                                   // (3, 4)
	fmt.Printf("Position: %v\n", p)                  // Position: (3, 4)
	fmt.Println([]point{{x: 1, y: 2}, {x: 5, y: 6}}) // [(1, 2) (5, 6)]

	// size has no String method, so it prints in the usual struct form.
	fmt.Println(size{w: 3, h: 4}) // {3 4}

	var s fmt.Stringer = p
	fmt.Println(s.String()) // (3, 4)
}