装饰者模式

  装饰者模式：动态地将责任附加到对象上。想要扩展功能，装饰者提供有别于继承的另一种选择。——《HEAD FIRST 设计模式》

  我的golang代码：

package decorator

//////////////////////////////////
type Beverage interface {
    GetDescription() string
    Cost() int
}

type CondimentDecorator interface {
    GetDescription() string
    Cost() int
}

//////////////////////////////////
type HouseBlend struct {
}

func (d *HouseBlend) Cost() int {
    return 1
}

func (d *HouseBlend) GetDescription() string {
    return "HouseBlend"
}

type DarkRoast struct {
}

func (d *DarkRoast) Cost() int {
    return 2
}

func (d *DarkRoast) GetDescription() string {
    return "DarkRoast"
}

type Espresso struct {
}

func (d *Espresso) Cost() int {
    return 3
}

func (d *Espresso) GetDescription() string {
    return "Espresso"
}

type Decaf struct {
}

func (d *Decaf) Cost() int {
    return 4
}

func (d *Decaf) GetDescription() string {
    return "Decaf"
}

///////////////////////////////////
type Milk struct {
    beverage Beverage
}

func NewMilk(b Beverage) *Milk {
    r := new(Milk)
    r.beverage = b

    return r
}

func (d *Milk) Cost() int {
    return d.beverage.Cost() + 1
}

func (d *Milk) GetDescription() string {
    return d.beverage.GetDescription() + ",Milk"
}

type Mocha struct {
    beverage Beverage
}

func NewMocha(b Beverage) *Mocha {
    r := new(Mocha)
    r.beverage = b

    return r
}

func (d *Mocha) Cost() int {
    return d.beverage.Cost() + 2
}

func (d *Mocha) GetDescription() string {
    return d.beverage.GetDescription() + ",Mocha"
}

type Soy struct {
    beverage Beverage
}

func NewSoy(b Beverage) *Soy {
    r := new(Soy)
    r.beverage = b

    return r
}

func (d *Soy) Cost() int {
    return d.beverage.Cost() + 3
}

func (d *Soy) GetDescription() string {
    return d.beverage.GetDescription() + ",Soy"
}

type Whip struct {
    beverage Beverage
}

func NewWhip(b Beverage) *Whip {
    r := new(Whip)
    r.beverage = b

    return r
}

func (d *Whip) Cost() int {
    return d.beverage.Cost() + 4
}

func (d *Whip) GetDecription() string {
    return d.beverage.GetDescription() + ",Whip"
}

   个人感悟：待留。