go get -u github.com/garenchan/go-decorator

package main

import (
	"fmt"

	"github.com/garenchan/go-decorator"
)

func sum(a, b int) int {
	fmt.Printf("%d + %d\n", a, b)
	return a + b
}

func main() {
	mySum := sum

        // Use TimeIT to decorate sum function, and get a new function mySum
	decorator.Decorate(&mySum, sum, decorator.TimeIt)

	// mySum will print the cost time.
	ret := mySum(1, 2)

	// Here will print 3.
	fmt.Println(ret)
}

= 2 { divisor := in[1].Interface().(int) if divisor == 0 { return []reflect.Value{reflect.ValueOf(0)} } } return targetFunc.Call(in) } func main() { myDiv := div decorator.Decorate(&myDiv, div, safeDiv) // Here will print 0. fmt.Println(myDiv(1, 0)) // Here will print 1. fmt.Println(myDiv(1, 1)) } ">

package main

import (
	"fmt"
	"reflect"

	"github.com/garenchan/go-decorator"
)

// div integer division
func div(a, b int) int {
	return a / b
}

// safeDiv returns 0 when the divisor is 0
func safeDiv(targetFunc reflect.Value, in []reflect.Value) (out []reflect.Value) {
	if len(in) >= 2 {
		divisor := in[1].Interface().(int)
		if divisor == 0 {
			return []reflect.Value{reflect.ValueOf(0)}
		}
	}

	return targetFunc.Call(in)
}

func main() {
	myDiv := div
	decorator.Decorate(&myDiv, div, safeDiv)

	// Here will print 0.
	fmt.Println(myDiv(1, 0))

	// Here will print 1.
	fmt.Println(myDiv(1, 1))
}