建造者模式

• 概念：使用多个复杂的对象构造成一个复杂的对象。
• 目的：将复杂的构建与表现相分离，使同样的构建可以构建不同的表示。
  -顺便整理了点小demo:

package pattern

import (
    "fmt"
    "testing"
)

func TestBuilder(t *testing.T) {
    // shenzhen glasses
    director := Director{OriginPrice: 1.1}

    var builder Builder = &ShenzhenGlasses{}
    shenzhenGlasses := director.Creator(builder)
    fmt.Printf("glasses comes from %s, price is %G \n", shenzhenGlasses.From, shenzhenGlasses.Price)

    // guangzhou glasses
    builder = &GuangzhouGlasses{}
    guangzhouGlasses := director.Creator(builder)
    fmt.Printf("glasses comes from %s, price is %G", guangzhouGlasses.From, guangzhouGlasses.Price)
}

type Glasses struct {
    Price float64
    From string
}

type Builder interface {
    SetPrice(price float64) Builder
    SetFrom() Builder
    GetGlasses() *Glasses
}

type ShenzhenGlasses struct {
    glasses *Glasses
}

type GuangzhouGlasses struct {
    glasses *Glasses
}

func (g *ShenzhenGlasses) SetPrice(price float64) Builder {
    if g.glasses == nil {
        g.glasses = &Glasses{}
    }
    g.glasses.Price = price * 2.1

    return g
}

func (g *ShenzhenGlasses) SetFrom() Builder {
    if g.glasses == nil {
        g.glasses = &Glasses{}
    }
    g.glasses.From = "shenzhen"

    return g
}

func (g *ShenzhenGlasses) GetGlasses() *Glasses {
    return g.glasses
}


func (g *GuangzhouGlasses) SetPrice(price float64) Builder {
    if g.glasses == nil {
        g.glasses = &Glasses{}
    }
    g.glasses.Price = price * 1.2

    return g
}

func (g *GuangzhouGlasses) SetFrom() Builder {
    if g.glasses == nil {
        g.glasses = &Glasses{}
    }
    g.glasses.From = "guangzhou"

    return g
}

func (g *GuangzhouGlasses) GetGlasses() *Glasses {
    return g.glasses
}

type Director struct {
    OriginPrice float64
}

func (d *Director) Creator(b Builder) *Glasses {
    return b.SetPrice(d.OriginPrice).SetFrom().GetGlasses()
}