Golang 延迟关闭

Question

我刚开始学习延迟。我想知道为什么第一个有效而第二个无效。我想知道他们之间有什么区别。第一:

func say(s string) {
    defer func() {
        if  r := recover(); r != nil {
            fmt.Println("Recovered in cleanup:", r)
        }
        wg.Done()
    }()
    for i := 0; i < 3; i++ {
        fmt.Println(s)
        time.Sleep(time.Millisecond * 100)
        if i == 2 {
            panic("oh")
        }
    }
}

第二个:

func cleanup(){
        if  r := recover(); r != nil {
            fmt.Println("Recovered in cleanup:", r)
        }
}

func say(s string) {
    defer func() {
        cleanup()
        wg.Done()
    }()
    for i := 0; i < 3; i++ {
        fmt.Println(s)
        time.Sleep(time.Millisecond * 100)
        if i == 2 {
            panic("oh")
        }
    }
}

Answer 1

specification says :

The return value of recover is nil if any of the following conditions holds:

...

• recover was not called directly by a deferred function.

cleanup() 函数由匿名延迟函数调用。重写代码以直接延迟 cleanup()。

func say(s string) {
    defer wg.Done()
    defer cleanup() // cleanup called directly by defer
    for i := 0; i < 3; i++ {
        fmt.Println(s)
        time.Sleep(time.Millisecond * 100)
        if i == 2 {
            panic("oh")
        }
    }
}