函数选项模式

1type Server struct {
2    host    string
3    port    int
4    timeout time.Duration
5    tls     bool
6}
7 
8type Option func(*Server)
9 
10func WithPort(port int) Option {
11    return func(s *Server) { s.port = port }
12}
13 
14func WithTimeout(d time.Duration) Option {
15    return func(s *Server) { s.timeout = d }
16}
17 
18func WithTLS() Option {
19    return func(s *Server) { s.tls = true }
20}
21 
22func NewServer(host string, opts ...Option) *Server {
23    s := &Server{
24        host:    host,
25        port:    8080,      // 默认值
26        timeout: 30 * time.Second,
27    }
28    for _, opt := range opts {
29        opt(s)
30    }
31    return s
32}
33 
34// 使用
35server := NewServer("0.0.0.0",
36    WithPort(3000),
37    WithTimeout(time.Minute),
38    WithTLS(),
39)