CODEWITHSUNDEEP
functiongoargumentschannel
Ritchie Borja
Ritchie Borja

Reputation: 103

What's the difference between the following function arguments involving channels in Go?

This code with the channel operator in the function argument:

func Worker(item <- chan string)

And this code without the channel operator in the function argument:

func Worker(item chan string)

Upvotes: 0

Views: 69

Answers (3)

Adriel Artiza
Adriel Artiza

Reputation: 337

You can try this code example to simulate channel direction.

// func Worker(item <- chan string) # Send or Receive
// func Worker(item chan string)    # Bidirectional

func sendOrRecvFunc(item <-chan string, msg *string) {
    *msg = <- item // send
}

func bidirectionalFunc(item chan string, msg string) {
    item <- msg // receive
}

func main() {

    // e.g Send or Receive
    var msg1 string

    item1 := make(chan string,1)

    item1 <- "message1" // receive

    sendOrRecvFunc(item1,&msg1)

    fmt.Println(msg1)

    //---------------------------------------------

    // e.g Bidirectional
    item2 := make(chan string,1)

    bidirectionalFunc(item2,"message2")

    msg2 := <- item2 // send

    fmt.Println(msg2)

}

// Output:
message1
message2

Upvotes: 0

Harsh Vardhan
Harsh Vardhan

Reputation: 665

func Worker(item <- chan string)

Here item is a send channel. You can only send value to it can't receive from it.

func Worker(item chan string)

Here item is a bidirectional channel. Both send and receiving is possible.

Upvotes: 1

leaf bebop
leaf bebop

Reputation: 8222

The optional <- operator specifies the channel direction, send or receive. If no direction is given, the channel is bidirectional. A channel may be constrained only to send or only to receive by conversion or assignment.

From golang spec: https://golang.org/ref/spec#Channel_types

Upvotes: 5

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