// Chapter 28 example: changing a struct held in a map, the two ways that work.
// Run with: go run exercises/28/05-map-of-structs.go

package main

import "fmt"

type critter struct {
	name   string
	energy int
}

func main() {
	// A map of structs: copy out, change the copy, put it back.
	team := map[string]critter{
		"spark": {name: "Spark", energy: 3},
	}

	c := team["spark"]
	c.energy = 2
	team["spark"] = c
	fmt.Println(team["spark"].energy) // 2

	// A map of pointers: change the critter through the pointer.
	pets := map[string]*critter{
		"bolt": {name: "Bolt", energy: 2},
	}

	pets["bolt"].energy = 1
	fmt.Println(pets["bolt"].energy) // 1

	// A missing key in a map of pointers gives nil, so check with ok first.
	pet, ok := pets["nova"]
	if !ok {
		fmt.Println("No critter called nova.")
		return
	}
	fmt.Println(pet.energy)
}