【寒江雪】Go实现Builder Pattern

Builder Pattern

  生成器模式将复杂对象的构造与表示分开，以便相同的构建过程可以创建不同的表示形式。

  然而在Go语言中，如果向Builder传递一个结构，代码中就会充满检查代码，判断某个字段是否为空。为了避免这种现象，我们只需要在Builder中放置一个配置结构。

实现

  我们来实现一个构造器构造一个灯的过程。

// 先定义几个类型
type Color string
type LampStatus bool
type Brand string

// 定义颜色常量
const (
BlueColor  Color = "blue"
GreenColor       = "green"
RedColor         = "red"
)

// 定义品牌常量
const (
OppleBulb Brand = "OPPLE"
Osram           = "OSRAM"
)

//  Lamp Builder define
type Builder interface {
Color(Color) LampBuilder
Brand(Brand) LampBuilder
Build() LampOperation
}

type LampBuilder struct {
Lamp    // 配置结构
}

func (lb LampBuilder) Color(c Color) LampBuilder {
lb.color=c
return lb
}

func (lb LampBuilder) Brand(b Brand) LampBuilder {
lb.brand=b
return lb
}

func (lb LampBuilder) Build() LampOperation {
// 新的产品产生过程
lamp := Lamp{color: lb.color, brand: lb.brand, status: false}
return lamp
}

func NewBuilder() Builder {
return LampBuilder{}
}

type LampOperation interface {
Open() error
Close() error
Product
4000
ionIllustrative()
}

// 灯的定义
type Lamp struct {
color  Color
brand  Brand
status LampStatus
}

func (l Lamp) Open() error {
if l.status {
return errors.New("Lamp is opened")
}
fmt.Println("Open lamp.")
l.status = true
return nil
}

func (l Lamp) Close() error {
if !l.status {
return errors.New("Lamp is closed")
}
fmt.Println("Close lamp.")
l.status = true
return nil;
}

func (l Lamp) ProductionIllustrative() {
fmt.Println("I'm a lamp.")
fmt.Println("Color:" + l.color)
fmt.Println("Brand:" + l.brand)
}

  使用:

func main(){
b := builder.NewBuilder()
lamp_1 := b.Color(builder.BlueColor).Brand(builder.Osram).Build()
lamp_1.Open()
lamp_1.ProductionIllustrative()

lamp_2 := b.Color(builder.GreenColor).Brand(builder.OppleBulb).Build()
lamp_2.ProductionIllustrative()
}

Author:寒江雪

Date:2018 03 10