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Go 装饰模式讲解和代码示例

装饰是一种结构设计模式， 允许你通过将对象放入特殊封装对象中来为原对象增加新的行为。

由于目标对象和装饰器遵循同一接口， 因此你可用装饰来对对象进行无限次的封装。 结果对象将获得所有封装器叠加而来的行为。

** 进一步了解装饰模式 **

概念示例

** pizza.go:  零件接口

package main

type IPizza interface {
    getPrice() int
}

** veggieMania.go:  具体零件

package main

type VeggeMania struct {
}

func (p *VeggeMania) getPrice() int {
    return 15
}

** tomatoTopping.go:  具体装饰

package main

type TomatoTopping struct {
    pizza IPizza
}

func (c *TomatoTopping) getPrice() int {
    pizzaPrice := c.pizza.getPrice()
    return pizzaPrice + 7
}

** cheeseTopping.go:  具体装饰

package main

type CheeseTopping struct {
    pizza IPizza
}

func (c *CheeseTopping) getPrice() int {
    pizzaPrice := c.pizza.getPrice()
    return pizzaPrice + 10
}

** main.go:  客户端代码

package main

import "fmt"

func main() {

    pizza := &VeggeMania{}

    //Add cheese topping
    pizzaWithCheese := &CheeseTopping{
        pizza: pizza,
    }

    //Add tomato topping
    pizzaWithCheeseAndTomato := &TomatoTopping{
        pizza: pizzaWithCheese,
    }

    fmt.Printf("Price of veggeMania with tomato and cheese topping is %d\n", pizzaWithCheeseAndTomato.getPrice())
}

** output.txt:  执行结果

Price of veggeMania with tomato and cheese topping is 32