golangdefer

In Go, defer is a statement that schedules a function call to be executed after the surrounding function returns. The defer statement is often used to ensure that resources are released, like closing a file or releasing a mutex, regardless of whether the function completes successfully or not.

For example:

func exampleFunc() {
   defer fmt.Println("This will be printed last")
   fmt.Println("This will be printed first")
}

In the above code, the function exampleFunc() prints two lines of text. However, the defer statement ensures that the fmt.Println("This will be printed last") statement is executed after the function has completed, and thus it will be printed last.

Multiple defer statements can be used in a function, and they will be executed in the reverse order that they were defined.

func exampleFunc() {
   defer fmt.Println("This will be printed last")
   defer fmt.Println("This will be printed second to last")
   fmt.Println("This will be printed first")
}

In this case, the output will be:

This will be printed first
This will be printed second to last
This will be printed last