Inheritance in GO using interface + struct

This post describes inheritance using interface and struct. Do visit our Inheritance in Go Complete Guide post for full reference

OOP: Inheritance in GOLANG complete guide

Go supports inheritance by embedding struct or using interface. There are different ways of doing it and each having some limitations. The different ways are:

1. By using embedded struct – The parent struct is embedded in child struct. The limitation is that subtyping is not possible with this approach. You cannot pass the child struct to a function that expects base. Refer this link for more details – Inheritance using Struct
2. By using interfaces – Subtyping is possible but the limitation is that one has no way to refer to common properties. Refer this link for more details – Inheritance using Interface
3. By using interface + struct – This fixes the limitations of above two approach but one limitation is that overriding methods is not possible. But there is workaround. Current post describes this approach

Details:

In this approach, the base struct is embedded in child struct and base struct implements all methods of the common interface. So child struct can:

1. Access methods and properties of base struct
2. Since base struct implements all functions of the common interface, the common interface itself can be used for subtyping.

package main

import "fmt"

type iBase interface {
	say()
}

type base struct {
	value string
}

func (b *base) say() {
	fmt.Println(b.value)
}

type child struct {
	base  //embedding
	style string
}

func check(b iBase) {
	b.say()
}

func main() {
	base := base{value: "somevalue"}
	child := &child{
		base:  base,
		style: "somestyle",
	}
	child.say()
	check(child)
}

Output:

somevalue
somevalue