1. package main
    3. import "fmt"
    5. type options struct {
    6.     cache  bool
    7.     logger string
    8. }
    10. type Option interface {
    11.     apply(*options)
    12. }
    14. type cacheOption bool
    16. func (c cacheOption) apply(opts *options) {
    17.     opts.cache = bool(c)
    18. }
    20. func WithCache(c bool) Option {
    21.     return cacheOption(c)
    22. }
    24. type loggerOption struct {
    25.     Log string
    26. }
    28. func (l loggerOption) apply(opts *options) {
    29.     opts.logger = l.Log
    30. }
    32. func WithLogger(log string) Option {
    33.     return loggerOption{Log: log}
    34. }
    36. // Open creates a connection.
    37. func Open(
    38.     addr string,
    39.     opts ...Option,
    40. ){
    41.     options := options{
    42.         cache:  true,
    43.         logger: "hello",
    44.     }
    45.     fmt.Println(">>addr: ",addr)
    46.     fmt.Println(">>opts: ",opts)
    47.     for _, o := range opts {
    48.         o.apply(&options)
    49.     }
    50. }
    52. func main(){
    53.     var option Option
    54.     option = new(cacheOption)
    55.     option.apply(&options{cache:true})
    57.     var option1 Option
    58.     option1 = new(loggerOption)
    59.     option1.apply(&options{logger:"hi,"})
    61.     Open("localhost",[]Option{option,option1}...)
    62. }