Interface implementation

main.go

package main

import (
	"fmt"
)

type Entity interface {
	Voice() string
}

type Animal struct {
	Say string
}

func (a Animal) Voice() string {
	return a.Say
}

func main() {
	// Impl Dog.
	var dog Entity = Animal{"Woof, Woof!"}
	fmt.Println("Dog say: ", dog.Voice())

	// Impl Cat.
	var cat = Animal{"Meow, meow!"}
	fmt.Println("Cat say: ", cat.Voice())

	// Compare types.
	fmt.Println("Compare types: ", dog == cat)

	// ==================================
	fmt.Println("\n========================\n")

	// Init Cat1.
	var cat1 Entity

	// Impl Cat1.
	cat1 = Animal{"Meow, meow!"}
	fmt.Println("Cat1 say: ", cat1.Voice())

	// Impl Cat2.
	var cat2 = Animal{"Meow, meow!"}
	fmt.Println("Cat2 say: ", cat2.Voice())

	// Compare types.
	fmt.Println("Compare cats types: ", cat1 == cat2)
}