Go Example

package main

type button struct {
    command command
}

func (b *button) press() {
    b.command.execute()
}

package main

type command interface {
    execute()
}

package main

type device interface {
    on()
    off()
}

package main

type offCommand struct {
    device device
}

func (c *offCommand) execute() {
    c.device.off()
}

package main

type onCommand struct {
    device device
}

func (c *onCommand) execute() {
    c.device.on()
}

package main

import "fmt"

type tv struct {
    isRunning bool
}

func (t *tv) on() {
    t.isRunning = true
    fmt.Println("Turning tv on")
}

func (t *tv) off() {
    t.isRunning = false
    fmt.Println("Turning tv off")
}

package main

func main() {
    tv := &tv{}

    onCommand := &onCommand{
        device: tv,
    }

    offCommand := &offCommand{
        device: tv,
    }

    onButton := &button{
        command: onCommand,
    }
    onButton.press()

    offButton := &button{
        command: offCommand,
    }
    offButton.press()
}

Turning tv on
Turning tv off