Simple Go Interfaces Example

event_interface_example.go

package main

// Run at https://play.golang.org/p/QDc3-94kqJ

import (
	"fmt"
	"reflect"
)

type Event interface {
	// The following two properties are the Event types required method signatures
	SetMessage(msg string)
	GetMessage() string
	SetCode(c uint8)
	GetCode() uint8
	Print()
}

type NoticeEvent struct {
	message string
	code    uint8
}

func (evt *NoticeEvent) SetMessage(msg string) {
	evt.message = msg
}
func (evt *NoticeEvent) SetCode(c uint8) {
	evt.code = c
}
func (evt *NoticeEvent) GetMessage() string {
	return evt.message
}
func (evt *NoticeEvent) GetCode() uint8 {
	return evt.code
}
func (evt *NoticeEvent) Print() {
	fmt.Printf("[NOTICE] %s (%d)\n", evt.message, evt.code)
}

type ErrorEvent struct {
	message string
	code    uint8
}

func (evt *ErrorEvent) SetMessage(msg string) {
	evt.message = msg
}
func (evt *ErrorEvent) SetCode(c uint8) {
	evt.code = c
}
func (evt *ErrorEvent) GetMessage() string {
	return evt.message
}
func (evt *ErrorEvent) GetCode() uint8 {
	return evt.code
}
func (evt *ErrorEvent) Print() {
	fmt.Printf("[ERROR] %s (%d)\n", evt.message, evt.code)
}

type CustomEvent struct {
	message string
	code    uint8
	level   string
}

func (evt *CustomEvent) SetMessage(msg string) {
	evt.message = msg
}
func (evt *CustomEvent) SetCode(c uint8) {
	evt.code = c
}
func (evt *CustomEvent) GetMessage() string {
	return evt.message
}
func (evt *CustomEvent) GetCode() uint8 {
	return evt.code
}
func (evt *CustomEvent) Print() {
	fmt.Printf("[CUSTOM::%s] %s (%d)\n", evt.level, evt.message, evt.code)
}

func main() {
	var evtNotice Event
	evtNotice = &NoticeEvent{}
	evtNotice.SetMessage("This is a sample notice")
	evtNotice.SetCode(2)
	if evt, ok := evtNotice.(*NoticeEvent); ok {
		evt.Print()
		fmt.Println(" -> Type:", reflect.TypeOf(evt))
	}

	var evtError Event
	evtError = &ErrorEvent{}
	evtError.SetMessage("This is a sample error")
	evtError.SetCode(4)
	if evt, ok := evtError.(*ErrorEvent); ok {
		evt.Print()
		fmt.Println(" -> Type:", reflect.TypeOf(evt))
	}

	var evtCustom Event
	evtCustom = &CustomEvent{"This is a sample custom message which also has a level", 10, "debug"}
	if evt, ok := evtCustom.(*CustomEvent); ok {
		evt.Print()
		fmt.Println(" -> Type:", reflect.TypeOf(evt))
	}

}