Can I create channel without using the make function?-CodePudding

The following code works okay

func main() {
    c := make(chan string)
    go subRountine(c)
    fmt.Println(<-c)
}

func subRountine(c chan string) {
    c <- "hello"
}

Is there any other method to create a channel without the make function? Something like this but this sample does not work

func main() {
    var c chan string
    go subRountine(c)
    fmt.Println(<-c)
}

func subRountine(c chan string) {
    c <- "hello"
}

CodePudding user response：

TL;DR

No way around it: you must use make.

More details

var c chan string

merely declares a channel variable, but without initialising the channel! This is problematic because, as the language spec puts it

The value of an uninitialized channel is nil.

and

A nil channel is never ready for communication.

In other words, sending and/or receiving to a nil channel is blocking. Although nil channel values can be useful, you must initialise a channel at some stage if you ever want to perform channel communications (send or receive) on it.

As mkopriva writes in his comment, Go provides only one way of initialising a channel:

A new, initialized channel value can be made using the built-in function make, which takes the channel type and an optional capacity as arguments:
make(chan int, 100)

CodePudding user response：

No! Declaring a channel with var is different from creating it. Then you should create by make:

  var c chan string
  c = make(chan string)

With the difference that now you can make c in underlying scops and use it outside of them.

Note that you shouldn't put colons before the equals sign in this way.