go语言设计模式之builder

builder.go

package builder

type BuildProcess interface {
	SetWheels() BuildProcess
	SetSeats() BuildProcess
	SetStructure() BuildProcess
	GetVehicle() VehicleProduct
}

type ManufacturingDirector struct {
	builder BuildProcess
}

func (f *ManufacturingDirector) Construct() {
	//Implementation goes here
	f.builder.SetSeats().SetStructure().SetWheels()
}

func (f *ManufacturingDirector) SetBuilder(b BuildProcess) {
	//Implementation goes here
	f.builder = b
}

type VehicleProduct struct {
	Wheels    int
	Seats     int
	Structure string
}

type CarBuilder struct {
	v VehicleProduct
}

func (c *CarBuilder) SetWheels() BuildProcess {
	c.v.Wheels = 4
	return c
}

func (c *CarBuilder) SetSeats() BuildProcess {
	c.v.Seats = 5
	return c
}

func (c *CarBuilder) SetStructure() BuildProcess {
	c.v.Structure = "Car"
	return c
}

func (c *CarBuilder) GetVehicle() VehicleProduct {
	return c.v
}

type BikeBuilder struct {
	v VehicleProduct
}

func (b *BikeBuilder) SetWheels() BuildProcess {
	b.v.Wheels = 2
	return b
}

func (b *BikeBuilder) SetSeats() BuildProcess {
	b.v.Seats = 2
	return b
}

func (b *BikeBuilder) SetStructure() BuildProcess {
	b.v.Structure = "Motorbike"
	return b
}

func (b *BikeBuilder) GetVehicle() VehicleProduct {
	return b.v
}

　　

builder_test.go

package builder

import "testing"

func TestBuilderPattern(t *testing.T) {
	manufacturingComplex := ManufacturingDirector{}

	carBuilder := &CarBuilder{}
	manufacturingComplex.SetBuilder(carBuilder)
	manufacturingComplex.Construct()

	car := carBuilder.GetVehicle()

	if car.Wheels != 4 {
		t.Errorf("Wheels on a car must be 4 and they were %d\n", car.Wheels)
	}

	if car.Structure != "Car" {
		t.Errorf("Structure on a car must be 'Car' and was %s\n", car.Structure)
	}

	if car.Seats != 5 {
		t.Errorf("Seats on a car must be 4 and they were %d\n", car.Seats)
	}

	bikeBuiler := &BikeBuilder{}
	manufacturingComplex.SetBuilder(bikeBuiler)
	manufacturingComplex.Construct()

	motorbike := bikeBuiler.GetVehicle()
	motorbike.Seats = 1

	if motorbike.Wheels != 2 {
		t.Errorf("Wheels on a motobike must be 2 and they were %d\n", motorbike.Wheels)
	}

	if motorbike.Structure != "Motorbike" {
		t.Errorf("Structure on a motobike must be 'Motorbike' and was %s\n", motorbike.Structure)
	}

}