“不支持索引”：为接口提供索引吗？

Question

https://play.golang.org/p/qxhocI6mjY

In this play, I get this error : invalid operation: s[0] (type AlmostSlice does not support indexing) So I am wondering, is it possible to implement indexing ?

Given a struct like this :

type AlmostSlice struct {
    Entities []string
    Id       string
    Stuffs   string
}

Is it possible to make it support indexing ?

s := AlmostSlice{Id: "bar", Entities: []string{"foo"}}
... := s[0]
s[0] = "stuffs"

For example, by implementing something like this :

func (s *AlmostSlice) Index(i int) string {
    return s.Entities[i]
}

Answer 1

Good question. In other languages there are magic interfaces you can implement to do stuff like that but in Go the point is we don't have those things. So to answer your question, no as of 1.7 you can't implement indexing on a struct.