Select

Sometimes we have a single goroutine listening to multiple channels and want to process data in the order it comes through each channel.

A select statement is used to listen to multiple channels at the same time. It is similar to a switch statement but for channels.

select {
  case i, ok := <- chInts:
    fmt.Println(i)
  case s, ok := <- chStrings:
    fmt.Println(s)
}

The first channel with a value ready to be received will fire and its body will execute. If multiple channels are ready at the same time one is chosen randomly. The ok variable in the example above refers to whether or not the channel has been closed by the sender yet.

Assignment

Complete the logMessages function.

Use an infinite for loop and a select statement to log the emails and sms messages as they come in order across the two channels. Add a condition to return from the function when one of the two channels closes, whichever is first.

Use the logSms and logEmail functions to log the messages.