package main import ( "crypto/tls" "fmt" "time" ) // 业务实体 type Server struct { Addr string Port int Protocol string Timeout time.Duration MaxConns int TLS *tls.Config } // 高阶函数 type Option func(*Server) func Protocol(p string) Option { return func(server *Server) { server.Protocol = p } } func Timeout(timeout time.Duration) Option { return func(server *Server) { server.Timeout = timeout } } func MaxConns(maxconns int) Option { return func(server *Server) { server.MaxConns = maxconns } } func TLS(tls *tls.Config) Option { return func(server *Server) { server.TLS = tls } } func NewServer(addr string, port int, options ...func(*Server)) (*Server, error) { serv := Server{ Addr: addr, Port: port, Protocol: "tcp", Timeout: 30 * time.Second, MaxConns: 1000, TLS: nil, } for _, option := range options { option(&serv) } return &serv, nil } func main() { server, _ := NewServer("127.0.0.1", 9999, Protocol("UDP"), MaxConns(100)) fmt.Println(server.Protocol) fmt.Println(server.MaxConns) }