Meaning of a struct with embedded anonymous interface?

Question

sort package:

type Interface interface {
    Len() int
    Less(i, j int) bool
    Swap(i, j int)
}

...

type reverse struct {
    Interface
}
         


        

Answer 1

The statement

type reverse struct {
    Interface
}

enables you to initialize reverse with everything that implements the interface Interface. Example:

&reverse{sort.Intslice([]int{1,2,3})}

This way, all methods implemented by the embedded Interface value get populated to the outside while you are still able to override some of them in reverse, for example Less to reverse the sorting.

This is what actually happens when you use sort.Reverse. You can read about embedding in the struct section of the spec.