the 1st way we can code

GoCloud-Builder-model-way1.go

package ecs

import (
	"errors"
)

const errCommon = "ali-cloud create node miss required parameter: "

type CreateNode struct {
	RegionID                string //required
	ImageID                 string //required
	InstanceType            string //required
	SecurityGroupID         string //required
	ZoneID                  string //not necessary
	InstanceName            string //not necessary
	Description             string //not necessary
	InternetChargeType      string //not necessary
	InternetMaxBandwidthIn  int    //not necessary
	InternetMaxBandwidthOut int    //not necessary
	HostName                string //not necessary
	Password                string //not necessary
	IoOptimized             string //not necessary
	SystemDiskCategory      string //not necessary
	SystemDiskSize          string //not necessary
	SystemDiskName          string //not necessary
	SystemDiskDescription   string //not necessary
}

type CreateNodeBuilder struct {
	params *CreateNode
}

func NewCreateNodeBuilder() *CreateNodeBuilder {
	return &CreateNodeBuilder{}
}
func (b *CreateNodeBuilder) RegionID(regionID string) *CreateNodeBuilder {
	b.params.RegionID = regionID
	return b
}
func (b *CreateNodeBuilder) ImageID(imageID string) *CreateNodeBuilder {
	b.params.ImageID = imageID
	return b
}
func (b *CreateNodeBuilder) InstanceType(instanceType string) *CreateNodeBuilder {
	b.params.InstanceType = instanceType
	return b
}
func (b *CreateNodeBuilder) SecurityGroupID(securityGroupID string) *CreateNodeBuilder {
	b.params.SecurityGroupID = securityGroupID
	return b
}
func (b *CreateNodeBuilder) ZoneID(zoneID string) *CreateNodeBuilder {
	b.params.ZoneID = zoneID
	return b
}

//func
//.
//.
//.
//func


func (b *CreateNodeBuilder) Build() (*CreateNode, error) {
	if b.params.RegionID == "" {
		return nil, errors.New(errCommon + "RegionID")
	}
	if b.params.ImageID == "" {
		return nil, errors.New(errCommon + "ImageID")
	}
	if b.params.InstanceType == "" {
		return nil, errors.New(errCommon + "InstanceType")
	}
	if b.params.SecurityGroupID == "" {
		return nil, errors.New(errCommon + "SecurityGroupID")
	}
	return b.params, nil
}