panic/recover 1

package main

import "fmt"

func main() {
	defer func() {
		fmt.Print(recover())
	}()
	defer func() {
		defer fmt.Print(recover())
		defer panic(1)
		recover()
	}()
	defer recover()
	panic(2)
}

Choices:

• 21
• <nil>1
• <nil>2
• 1<nil>

Answer: 21

Run it on Go play.

Key points:

• The two recover calls at line 14 and 12 are no-op.
• The recover calls at line 10 catches the panic 2.
• The recover calls at line 7 catches the panic 1.

Please read Explain Panic/Recover Mechanism in Detail for details.

• slice: 1, 2, 3
• map: 1
• channel: 1
• loop: 1, 2, 3, 4
• switch: 1
• defer: 1, 2
• panic/recover: 1, 2
• reflect: 1, 2
• const: 1, 2, 3, 4
• operator: 1, 2, 3
• function call: 1
• scope: 1, 2
• nil: 1
• embedding: 1

(more are coming ...)