go_factory.go

// WARNING: This file is a simple annotation and don`t run

type Person struct {
  Name string
  Age int
}

func (p Person) Greet() {
  fmt.Println("Hi! I'm %s", p.Name)
}

# Simple factory
func NewPerson(name string, age int) Person {
  return Person{
    Name: name,
    Age: age,
  }
}


# Returns a point to Person
func NewPerson(name string, age int) *Person {
  return &Person{
    Name: name,
    Age: age,
  }
}

# Interface factories
type Person interface {
  Greet()
}

type person struct {
  name string
  age int
}

func (p person) Greet() {
  fmt.Println("Hi! I'm %s", p.name)
}

# now, NewPerson returns an interface, and not the person struct itself
func NewPerson(name string, age int) Person {
  return person{
    name: name,
    age, age,
  }
}

# You can use the same implementation to return a pointer of person
func NewPerson(name string, age int) Person {
  return &person{
    name: name,
    age: age,
  }
}

# Factory generators
type Animal struct {
  species string
  age int
}

type AnimalHouse struct {
  name string
  sizeInMeters int
}

type AnimalFactory struct {
  species string
  houseName string
}

func (af AnimalFactory) NewAnimal(age int) {
  return Animal{
    species: af.species,
    age: age,
  }
}

func (af AnimalFactory) NewHouse(sizeInMeters int) {
  return Animal{
    name: af.houseName,
    sizeInMeters: sizeInMeters,
  }
}

docFactory := AnimalFactory{
  species: "dog",
  houseName: "kennel",
}
dog := dogFactory.NewAnimal(2)
kennel := dogFactory.NewHouse(3)

horseFactory := AnimalFactory{
  species: "horse",
  houseName: "stable",
}
horseFactory.NewAnimal(12)
horseFactory.NewHouse(30)


// Factory functions
type Person struct {
  name string
  age int
}

func NewPersonFactory(age int) func(name string) Person {
  return func(name string) Person {
    return Person{
      name: name,
      age: age,
    }
  }
}

newBaby := NewPersonFactory(1)
baby:= newBaby("Leo")

newTeenager := NewPersonFactory(15)
teen := newTeenager("Kaka")