go chapter 3 - defer

https://www.cnblogs.com/bonelee/p/6861777.html

函数返回之前（或任意位置执行 return 语句之后）一刻才执行某个语句或函数。用法类似于面向对象编程语言 Java 和 C# 的 finally 语句块。

package main
import "fmt"

func main() {
	function1()
}

func function1() {
	fmt.Printf("In function1 at the top\n")
	defer function2()
	fmt.Printf("In function1 at the bottom!\n")
}

func function2() {
	fmt.Printf("function2: Deferred until the end of the calling function!")
}

　　

输出：

In Function1 at the top
In Function1 at the bottom!
Function2: Deferred until the end of the calling function!

当有多个 defer 行为被注册时，它们会以逆序执行（类似栈，即后进先出）

func f() {
	for i := 0; i < 5; i++ {
		defer fmt.Printf("%d ", i)
	}
}

　

输出：

4 3 2 1 0