Abstract Factory Design Pattern in Go

Note: Interested in understanding how all other design patterns can be implemented in GO. Please see this full reference – All Design Patterns in Go (Golang)

Definition:

Abstract Factory Design Pattern is a creational design pattern that lets you create a family of related objects. It is an abstraction over the factory pattern. It is best explained with an example. Let’s say we have two factories

• nike
• adidas

Imagine you need to buy a sports kit which has a shoe and short. Preferably most of the time you would want to buy a full sports kit of a similar factory i.e either nike or adidas. This is where the abstract factory comes into the picture as concrete products that you want is shoe and a short and these products will be created by the abstract factory of nike and adidas.
Both these two factories – nike and adidas implement iSportsFactory interface.
We have two product interfaces.

• iShoe – this interface is implemented by nikeShoe and adidasShoe concrete product.
• iShort – this interface is implemented by nikeShort and adidasShort concrete product.

Now let’s look at code

Code:

iSportsFactory.go

package main
import "fmt"
type iSportsFactory interface {
makeShoe() iShoe
makeShort() iShort
}
func getSportsFactory(brand string) (iSportsFactory, error) {
if brand == "adidas" {
return &adidas{}, nil
}
if brand == "nike" {
return &nike{}, nil
}
return nil, fmt.Errorf("Wrong brand type passed")
}

adidas.go

package main
type adidas struct {
}
func (a *adidas) makeShoe() iShoe {
return &adidasShoe{
shoe: shoe{
logo: "adidas",
size: 14,
},
}
}
func (a *adidas) makeShort() iShort {
return &adidasShort{
short: short{
logo: "adidas",
size: 14,
},
}
}

nike.go

package main
type nike struct {
}
func (n *nike) makeShoe() iShoe {
return &nikeShoe{
shoe: shoe{
logo: "nike",
size: 14,
},
}
}
func (n *nike) makeShort() iShort {
return &nikeShort{
short: short{
logo: "nike",
size: 14,
},
}
}

iShoe.go

package main
type iShoe interface {
setLogo(logo string)
setSize(size int)
getLogo() string
getSize() int
}
type shoe struct {
logo string
size int
}
func (s *shoe) setLogo(logo string) {
s.logo = logo
}
func (s *shoe) getLogo() string {
return s.logo
}
func (s *shoe) setSize(size int) {
s.size = size
}
func (s *shoe) getSize() int {
return s.size
}

adidasShoe.go

package main
type adidasShoe struct {
shoe
}

nikeShoe.go

package main
type nikeShoe struct {
shoe
}

iShort.go

package main
type iShort interface {
setLogo(logo string)
setSize(size int)
getLogo() string
getSize() int
}
type short struct {
logo string
size int
}
func (s *short) setLogo(logo string) {
s.logo = logo
}
func (s *short) getLogo() string {
return s.logo
}
func (s *short) setSize(size int) {
s.size = size
}
func (s *short) getSize() int {
return s.size
}

adidasShort.go

package main
type adidasShort struct {
short
}

nikeShort.go

package main
type nikeShort struct {
short
}

main.go

package main
import "fmt"
func main() {
adidasFactory, _ := getSportsFactory("adidas")
nikeFactory, _ := getSportsFactory("nike")
nikeShoe := nikeFactory.makeShoe()
nikeShort := nikeFactory.makeShort()
adidasShoe := adidasFactory.makeShoe()
adidasShort := adidasFactory.makeShort()
printShoeDetails(nikeShoe)
printShortDetails(nikeShort)
printShoeDetails(adidasShoe)
printShortDetails(adidasShort)
}
func printShoeDetails(s iShoe) {
fmt.Printf("Logo: %s", s.getLogo())
fmt.Println()
fmt.Printf("Size: %d", s.getSize())
fmt.Println()
}
func printShortDetails(s iShort) {
fmt.Printf("Logo: %s", s.getLogo())
fmt.Println()
fmt.Printf("Size: %d", s.getSize())
fmt.Println()
}

Output:

Logo: nike
Size: 14
Logo: nike
Size: 14
Logo: adidas
Size: 14
Logo: adidas
Size: 14