Error recovery in deferred function

error_recovery_in_defered_function.go

// Use go playground or https://github.com/traefik/yaegi to try

  func foo(v int) (rerr error) {
		if v%3 == 1 {
			defer func() {
				rerr = fmt.Errorf("error %d mod 3 => 1: overwrite", v)
			}()
		} else if v%3 == 2 {
			defer func() {
				err := fmt.Errorf("error %d mod 3 => 2: set error if nil", v)
				if rerr == nil {
					rerr = err
				}
			}()
		}

		if v%2 == 0 {
			return nil
		} else {
			return fmt.Errorf("error %d mod 2 => 1: main error", v)
		}
	}
  
  
// > foo(0)
// : <nil>
// > foo(1)
// : error 1 mod 3 => 1: overwrite
// > foo(2)
// : error 2 mod 3 => 2: set error if nil
// > foo(3)
// : error 3 mod 2 => 1: main error
// > foo(4)
// : error 4 mod 3 => 1: overwrite
// > foo(5)
// : error 5 mod 2 => 1: main error