defer

The defer statement defers the execution of a function until the surrounding function returns. Let's try to explain this a bit better. Inside a function, you have a defer in front of a function that you are calling. That function will execute essentially right before the function you are currently inside completes. Still confused? Perhaps an example will make this concept a little clearer:

package main
import "fmt"
func main() {
  defer done()
  fmt.Println("Main:  Start")
  fmt.Println("Main:  End")
}
func done() {
  fmt.Println("Now I am done")
}

The output for the defer example is as follows:

Main: Start
Main: End
Now I am done

Inside the main() function, we have a deferred function, defer done(). Notice that the done() function has no new or special syntax. It just has a simple print to stdout.

Next, we have two print statements. The results are interesting. The two print statements...