Golang排序：未实现sort.Interface（缺少Len方法）

Question

I´m having issues implementing the Sort interface in my Go app. Here´s the relevant code:

type Group struct {
   Teams []*Team
}

type Team struct {
    Points int
 }

    type Teams []*Team

            func (slice Teams) Len() int {
                return len(slice)
            }

            func (slice Teams) Less(i, j int) bool {
                return slice[i].Points < slice[j].Points
            }

            func (slice Teams) Swap(i, j int) {
                slice[i], slice[j] = slice[j], slice[i]
            }

So I wanna sort the groups´ teams on based on their points. But whenever I run

sort.Sort(group.Teams)

I get this error:

 cannot use group.Teams (type []*Team) as type sort.Interface in argument
to sort.Sort:   []*Team does not implement sort.Interface (missing Len
method)

Why is this?

Answer 1

[]*Team is not the same as Teams; you need to explicitly use or cast to the latter:

type Group struct {
   Teams Teams
}
sort.Sort(group.Teams)

Or:

type Group struct {
   Teams []*Team
}
sort.Sort(Teams(group.Teams))