How to write my own Sleep function using just time.After?

问题

I'm trying to write my own sleep function equivalent to time.Sleep using time.After in Go.

Here's the code. First attempt:

func Sleep(x int) {
  msg := make(chan int)
  msg := <- time.After(time.Second * x)
}

Second attempt:

func Sleep(x int) {
 time.After(time.Second * x)
}

Both return errors, can someone explain to me how to write a sleep function equivalent to time.Sleep using time.After and if possible when do I use channel?

回答1:

time.After() returns you a channel. And a value will be send on the channel after the specified duration.

So just receive a value from the returned channel, and the receive will block until the value is sent:

func Sleep(x int) {
    <-time.After(time.Second * time.Duration(x))
}

Your errors:

In your first example:

msg := <- time.After(time.Second * x)

msg is already declared, and so the Short variable declaration := cannot be used. Also the recieved value will be of type time.Time, so you can't even assign it to msg.

In your second example you need a type conversion as x is of type int and time.Second is of type time.Duration, and time.After() expects a value of type time.Duration.

来源：https://stackoverflow.com/questions/31942163/how-to-write-my-own-sleep-function-using-just-time-after