Last Updated: February 25, 2016
·
404
· ready4god2513

Understanding <- <-in

For newcomers to Golang (like myself) seeing c <- <-chan can be quite confusing. It isn't that channels in and of themselves are confusing, but the seemingly duplicate <- is deceptive. So I broke it down a bit and it really is simple. See this example in a simple channel fanning function.

func fanIn(input1, input2 <-chan string) <-chan string {
    c := make(chan string)
    // This looks confusing, but is actually simple.
    // This is easier to digest if we read from right to left.
    // On the right hand side we have a channel (input1).
    // When that channel gets data (<-input1), pass that data 
    // to the new channel (c <-).  So at run time we essentially have
    // c <- "my value"
    go func() {
        for {
            c <- <-input1
        }
    }()
    go func() {
        for {
            c <- <-input2
        }
    }()

    return c
}

Read more about concurrency here- http://blog.golang.org/pipelines