decorator pattern

decorator.go

package main

import "fmt"

type Printer interface {
  Print() string
}

type SimplePrinter struct {}

func (sp *SimplePrinter) Print() string {
  return "Hello"
}

type PrinterFunc func() string

func BoldDecorator(p Printer) Printer {
  return PrinterFunc(func() string {
    return "<b>" + p.Print() + "</b>"
  })
}

func (pf PrinterFunc) Print() string {
  return pf()
}

func main() {
  simplePrinter := &SimplePrinter{}
  boldPrinter := BoldDecorator(simplePrinter)
  fmt.Println(simplePrinter.Print()) // output: Hello
  fmt.Println(boldPrinter.Print()) // output: <b>Hello</b>
}