Go by Example: Inheritence (struct)

package main

import (
    "fmt"
)

Parent class

 
type Animal struct {
    name    string
    subject string
    food    string
}

Child Class

 
type Cat struct {
    Animal        // inherited from animal
    color  string // member specific for cat
}

Child Class

 
type Fish struct {
    Animal     // inherited from animal
    length int // member specific for Fish
}

method specific for cat

 
func (c Cat) talk() {
    fmt.Printf("my name is %s. and my color is %s\n", c.name, c.color)
}

method for all Animal

 
func (a Animal) eat() {
    fmt.Println(a.name + " only eat " + a.food + ", it belongs to" + a.subject)
}

in practice, we usually use interface for abstraction

 
type CanEatInterface interface {
    eat()
}

type Alien struct{}

Alien is not Animal, also implement CanEatInterface

 
func (a Alien) eat() {
    fmt.Println("nom nom")
}

Before Go support generics,
It’s common to use Interface to solve Parametric polymorphism.
It should accept AnimalInterface

 
func dinnerTime(a CanEatInterface) {
    fmt.Print("dinnerTime: ")
    a.eat()
}

func main() {
    a := Animal{name: "mammal", subject: "carnivorous", food: "maet"}
    a.eat()

declare Cat

 
    cat := Cat{Animal: Animal{name: "meow", subject: "cat", food: "fish"}, color: "black"}
    cat.eat()
    cat.talk()

declare Fish

 
    fish := Fish{Animal: Animal{name: "blublu", subject: "deep ocean", food: "seeweed"}, length: 6}

    dinnerTime(a)
    dinnerTime(cat)
    dinnerTime(fish)

    al := Alien{}
    dinnerTime(al)

}

go run examples/inheritence-struct.go
 
mammal only eat maet, it belongs tocarnivorous
meow only eat fish, it belongs tocat
my name is meow. and my color is black
dinnerTime: mammal only eat maet, it belongs tocarnivorous
dinnerTime: meow only eat fish, it belongs tocat
dinnerTime: blublu only eat seeweed, it belongs todeep ocean
dinnerTime: nom nom

Next example: Inheritence (interface).

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