Functional Options

[kagxin]

被初始化的 struct

• Addr 必选
• Port 必选
• TimeOut 为可选参数默认值为 10s
• MaxConns 为可选参数默认值为 100

type Server struct {
	Addr     string
	Port     int
	Timeout  time.Duration
	MaxConns int
}

使用多个初始化函数

import "time"

func New(addr string, port int, timeout *time.Duration, maxConns *int) *Server {
	s := &Server{
		Addr:     addr,
		Port:     port,
		Timeout:  10 * time.Second,
		MaxConns: 100,
	}
	if timeout != nil {
		s.Timeout = *timeout
	}
	if maxConns != nil {
		s.MaxConns = *maxConns
	}
	return s
}

func NewWithTimeout(addr string, port int, timeout time.Duration) *Server {
	s := &Server{
		Addr:     addr,
		Port:     port,
		Timeout:  timeout,
		MaxConns: 100,
	}
	return s
}

func NewWithMaxConns(addr string, port int, maxConns int) *Server {
	s := &Server{
		Addr:     addr,
		Port:     port,
		Timeout:  10 * time.Second,
		MaxConns: maxConns,
	}
	return s
}

func NewWithTimeoutMaxConns(addr string, port int, timeout time.Duration, maxConns int) *Server {
	s := &Server{
		Addr:     addr,
		Port:     port,
		Timeout:  timeout,
		MaxConns: maxConns,
	}
	return s
}

客户端初始化代码：

server := NewWithTimeout("127.0.0.1", 8000, 5*time.Second)

使用 Builder 模式

import "time"

type ServerBuilder struct {
	Server
}

func (sb *ServerBuilder) Create(addr string, port int) *ServerBuilder {
	return &ServerBuilder{
		Server: Server{
			Addr:     addr,
			Port:     port,
			Timeout:  10 * time.Second,
			MaxConns: 100,
		},
	}
}

func (sb *ServerBuilder) WithTimeout(timeout time.Duration) *ServerBuilder {
	sb.Server.Timeout = timeout
	return sb
}

func (sb *ServerBuilder) WithMaxConns(maxConns int) *ServerBuilder {
	sb.Server.MaxConns = maxConns
	return sb
}

func (sb *ServerBuilder) Build() *Server {
	return &sb.Server
}

客户端初始化代码：

sb := ServerBuilder{}
server := sb.Create("127.0.0.1", 8000).WithTimeout(5 * time.Second).Build()

functional options

type Option func(*Server)

func TimeOut(timeout time.Duration) Option {
	return func(s *Server) {
		s.Timeout = timeout
	}
}

func MaxConns(maxCon int) Option {
	return func(s *Server) {
		s.MaxConns = maxCon
	}
}

func New(addr string, port int, options ...Option) *Server {
	server := &Server{
		Addr:     addr,
		Port:     port,
		Timeout:  10 * time.Second,
		MaxConns: 100,
	}
	for _, opt := range options {
		opt(server)
	}
	return server
}

客户端初始化代码：

server := New("127.0.0.1", 8000, TimeOut(5*time.Second))