Go Decorator Example

deco.go

package main

import (
	"fmt"
	"math/rand"
	"time"
)

// An Adder adds two ints and returns an int
type Adder func(a int, b int) int

// Add boringly adds two integers and returns an int
func Add(a int, b int) int {
	return a + b
}

// GoofyAdd goofily adds two integers and returns an int
func GoofyAdd(adder Adder) Adder {
	return func(a int, b int) int {
		a += rand.Intn(100)
		return adder(a, b)
	}
}

// LossyAdd lossily adds two integers and returns an int
func LossyAdd(adder Adder) Adder {
	return func(a int, b int) int {
		b /= 2
		return adder(a, b)
	}
}

// GenerousAdd generously adds two integers and returns an int
func GenerousAdd(adder Adder) Adder {
	return func(a int, b int) int {
		a *= 10
		b += 1000
		return adder(a, b)
	}
}

func main() {
	rand.Seed(time.Now().UnixNano())
	adder := Add
	adder = GoofyAdd(Add)
	adder = LossyAdd(adder)
	adder = GenerousAdd(adder)
	adder = GenerousAdd(LossyAdd(GoofyAdd(LossyAdd(GenerousAdd(adder)))))
	fmt.Println(adder(123, 99))
}