interfaces.go

package main

import "log"

type EventLogger interface {
	Log() int
}

type EventA struct {
	Id          int
	Description string
}

func (e EventA) Log() int {
	log.Println(e.Id, e.Description)
	return e.Id
}

type EventB struct {
	Id          int
	Description string
	Location    string
}

func (e EventB) Log() int {
	log.Println(e.Id, e.Description, "at", e.Location)
	return e.Id
}

func logEvent(e EventLogger) {
	e.Log()
}

func main() {
	e1 := EventA{123, "Event A without location"}
	e2 := EventB{123, "Event B with location", "Pune"}

	e1.Log()
	logEvent(e1)
	logEvent(e2)
}