Basic example to demonstrate implementation of Generics in Go using interfaces.

generic_example.go

package main

import (
	"fmt"
	"sort"
)

type Person struct {
	Name string
	Age  int
}

type PersonList []Person

func (s PersonList) Len() int {
	return len(s)
}

func (s PersonList) Swap(i, j int) {
	s[i], s[j] = s[j], s[i]
}

func (s PersonList) Less(i, j int) bool {
	if s[i].Age == s[j].Age {
		// Default string comparison returns result by alphabetical order.
		return s[i].Name < s[j].Name
	}
	return s[i].Age < s[j].Age
}

func main() {
	persons := PersonList{
		Person{Name: "James", Age: 23},
		Person{Name: "Anthony", Age: 23},
		Person{Name: "Bob", Age: 24},
		Person{Name: "Charles", Age: 24},
		Person{Name: "Chris", Age: 32},
		Person{Name: "David", Age: 39},
	}
	fmt.Println("Before sort: ", persons)
	sort.Sort(persons)
	fmt.Println("After Sort: ", persons)
}