Using if condition in a defer statement

defer statement is used to do basic cleanup in go, deferred calls are executed when surrounding function returns.

f, err := os.Open(fileName)
    if err != nil {
        return
    }
defer src.Close()

We open a file and then use defer to close the file handle. Using defer makes sure that file handle is closed and we don’t have any bug in our code.But what if we want to make a decision(conditional) in defer, is that possible?

defer and named returns to rescue. Here we are using a form of defer that lets us do something if there is an error and something else if there is not an error.

package main

import (
	"errors"
	"fmt"
)

var toggleMe = true

func foo() (boo string, err error) {
	boo = "boo"

	defer func() {
		if err != nil {
			fmt.Printf(boo)
		} else {
			fmt.Println("bar")
		}
	}()

	if toggleMe {
		err = errors.New("an error occurred")
	}

	return
}

func main() {
	foo()
}

Playground

I don’t know if it is idiomatic go or not and that’s where I need your help, let me know if this is correct to do.