package main
type Computer interface {
    Print()
    SetPrinter(Printer)
}

package main
import "fmt"
type Mac struct {
    printer Printer
}
func (m *Mac) Print() {
    fmt.Println("Print request for mac")
    m.printer.PrintFile()
}
func (m *Mac) SetPrinter(p Printer) {
    m.printer = p
}

package main
import "fmt"
type Windows struct {
    printer Printer
}
func (w *Windows) Print() {
    fmt.Println("Print request for windows")
    w.printer.PrintFile()
}
func (w *Windows) SetPrinter(p Printer) {
    w.printer = p
}

package main
type Printer interface {
    PrintFile()
}

package main
import "fmt"
type Epson struct {
}
func (p *Epson) PrintFile() {
    fmt.Println("Printing by a EPSON Printer")
}

package main
import "fmt"
type Hp struct {
}
func (p *Hp) PrintFile() {
    fmt.Println("Printing by a HP Printer")
}

package main
import "fmt"
func main() {
    hpPrinter := &Hp{}
    epsonPrinter := &Epson{}
    macComputer := &Mac{}
    macComputer.SetPrinter(hpPrinter)
    macComputer.Print()
    fmt.Println()
    macComputer.SetPrinter(epsonPrinter)
    macComputer.Print()
    fmt.Println()
    winComputer := &Windows{}
    winComputer.SetPrinter(hpPrinter)
    winComputer.Print()
    fmt.Println()
    winComputer.SetPrinter(epsonPrinter)
    winComputer.Print()
    fmt.Println()
}