Golang : How To Use Panic and Recover

In this tutorial we will understand how panic function works and how to "interrupt and recover" from the panic.

First, let's examine Panic function

 package main

  import "fmt"

  func startPanic() {
 defer func() {
 fmt.Println("This will APPEAR")
 }()
 panic("noooo!")
  }

  func main() {
 fmt.Println("Starting to panic...")
 startPanic()
 fmt.Println("This WILL NOT APPEAR ")
  }

Output :

Starting to panic..

This will APPEAR

panic: noooo!

as you can see from the output. The string "This WILL NOT APPEAR" .... well, will not appear because the Panic function was invoked before the fmt.Println("This WILL NOT APPEAR ").

There are times when we need to recover from the panic and move on with life. This code below will demonstrate just that :

  package main

  import "fmt"

  func startPanic() {
 defer func() {
 if error := recover(); error != nil {
 fmt.Println("Recovering....", error)
 }
 }()
 panic("noooo!")
  }

  func main() {
 fmt.Println("Starting to panic...")
 startPanic()
 fmt.Println("This will APPEAR because of Recover")
  }

Output :

Starting to panic...

Recovering.... noooo!

This will APPEAR because of Recover

What happen here is that we manage to catch the error with the recover() function.

  if error := recover(); error != nil {
 fmt.Println("Recovering....", error)
  }

You can further enhance the error handling depending on your needs. Learn more at http://blog.golang.org/error-handling-and-go

Hope this tutorial will be helpful for those learning Go.