Go - reflection example

reflect-main.go

package main

import (
	"fmt"
	"reflect"
)

type Date struct {
	Day   int
	Month int
	Year  int
}

type Person struct {
	Name string
	DOB  Date
}

func main() {
	changeName()
	changeDateOfBirth()
}

func changeName() {
	person := Person{}
	rvName := reflect.ValueOf(&person.Name)

	printTypeAndSettability(rvName)

	rvName.Elem().SetString("test user")

	fmt.Println(person.Name)

}

func changeDateOfBirth() {
	person := Person{}

	rvDOB := reflect.New(
		reflect.Indirect(
			reflect.ValueOf(reflect.ValueOf(person).FieldByName("DOB").Interface()),
		).Type(),
	)

	printTypeAndSettability(rvDOB)

	newDate := Date{Day: 20, Month: 12, Year: 1980}
	rvDOB.Elem().Set(reflect.ValueOf(newDate))

	reflect.ValueOf(&person.DOB).Elem().Set(rvDOB.Elem())

	fmt.Printf("%v, %v\n", rvDOB.Elem().Interface(), person.DOB)
}

func printTypeAndSettability(thing reflect.Value) {
	fmt.Printf("type: %s, canSet: as pointer? %v, Elem()? %v\n", thing.Type().String(), thing.CanSet(), thing.Elem().CanSet())
}