comparator in golang code example

Example: golang custom sort

type Person struct {
    Name string
    Age  int
}

// ByAge implements sort.Interface based on the Age field.
type ByAge []Person

func (a ByAge) Len() int           { return len(a) }
func (a ByAge) Less(i, j int) bool { return a[i].Age < a[j].Age }
func (a ByAge) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

func main() {
    family := []Person{
        {"Alice", 23},
        {"Eve", 2},
        {"Bob", 25},
    }
    sort.Sort(ByAge(family))
    fmt.Println(family) // [{Eve 2} {Alice 23} {Bob 25}]
}