Abstract Factory in Go
Abstract Factory is a creational design pattern, which solves the problem of creating entire product families without specifying their concrete classes.
Abstract Factory defines an interface for creating all distinct products but leaves the actual product creation to concrete factory classes. Each factory type corresponds to a certain product variety.
The client code calls the creation methods of a factory object instead of creating products directly with a constructor call (new operator). Since a factory corresponds to a single product variant, all its products will be compatible.
Client code works with factories and products only through their abstract interfaces. This lets the client code work with any product variants, created by the factory object. You just create a new concrete factory class and pass it to the client code.
If you can’t figure out the difference between various factory patterns and concepts, then read our Factory Comparison.
Conceptual Example
Say, you need to buy a sports kit, a set of two different products: a pair of shoes and a shirt. You would want to buy a full sports kit of the same brand to match all the items.
If we try to turn this into code, the abstract factory will help us create sets of products so that they would always match each other.
iSportsFactory.go: Abstract factory interface
package main
import "fmt"
type ISportsFactory interface {
makeShoe() IShoe
makeShirt() IShirt
}
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: Concrete factory
package main
type Adidas struct {
}
func (a *Adidas) makeShoe() IShoe {
return &AdidasShoe{
Shoe: Shoe{
logo: "adidas",
size: 14,
},
}
}
func (a *Adidas) makeShirt() IShirt {
return &AdidasShirt{
Shirt: Shirt{
logo: "adidas",
size: 14,
},
}
}
nike.go: Concrete factory
package main
type Nike struct {
}
func (n *Nike) makeShoe() IShoe {
return &NikeShoe{
Shoe: Shoe{
logo: "nike",
size: 14,
},
}
}
func (n *Nike) makeShirt() IShirt {
return &NikeShirt{
Shirt: Shirt{
logo: "nike",
size: 14,
},
}
}
iShoe.go: Abstract product
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: Concrete product
package main
type AdidasShoe struct {
Shoe
}
nikeShoe.go: Concrete product
package main
type NikeShoe struct {
Shoe
}
iShirt.go: Abstract product
package main
type IShirt interface {
setLogo(logo string)
setSize(size int)
getLogo() string
getSize() int
}
type Shirt struct {
logo string
size int
}
func (s *Shirt) setLogo(logo string) {
s.logo = logo
}
func (s *Shirt) getLogo() string {
return s.logo
}
func (s *Shirt) setSize(size int) {
s.size = size
}
func (s *Shirt) getSize() int {
return s.size
}
adidasShirt.go: Concrete product
package main
type AdidasShirt struct {
Shirt
}
nikeShirt.go: Concrete product
package main
type NikeShirt struct {
Shirt
}
main.go: Client code
package main
import "fmt"
func main() {
adidasFactory, _ := GetSportsFactory("adidas")
nikeFactory, _ := GetSportsFactory("nike")
nikeShoe := nikeFactory.makeShoe()
nikeShirt := nikeFactory.makeShirt()
adidasShoe := adidasFactory.makeShoe()
adidasShirt := adidasFactory.makeShirt()
printShoeDetails(nikeShoe)
printShirtDetails(nikeShirt)
printShoeDetails(adidasShoe)
printShirtDetails(adidasShirt)
}
func printShoeDetails(s IShoe) {
fmt.Printf("Logo: %s", s.getLogo())
fmt.Println()
fmt.Printf("Size: %d", s.getSize())
fmt.Println()
}
func printShirtDetails(s IShirt) {
fmt.Printf("Logo: %s", s.getLogo())
fmt.Println()
fmt.Printf("Size: %d", s.getSize())
fmt.Println()
}
output.txt: Execution result
Logo: nike
Size: 14
Logo: nike
Size: 14
Logo: adidas
Size: 14
Logo: adidas
Size: 14
