go channels / published by https://github.com/dacr/code-examples-manager #133f6548-95e4-4630-ac02-5a56f36b343c/f7e80500578717ba90eb8e8bb0b6a210f7f8b3a7

concurrency-channels.go

/*?sr/bin/true; exec /usr/bin/env nix-shell -p go --run "go run $0" #*/
// summary : go channels
// keywords : go, channels, @testable
// publish : gist
// authors : David Crosson
// license : Apache NON-AI License Version 2.0 (https://raw.githubusercontent.com/non-ai-licenses/non-ai-licenses/main/NON-AI-APACHE2)
// id : 133f6548-95e4-4630-ac02-5a56f36b343c
// created-on : 2025-03-27T16:03:54+01:00
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : nix-shell -p go --run "go run $file"
package main

import "fmt"

func main() {
	// channels
	// - can be thought as a FIFO queue (empty by default)
	// - Block at write if no free slot or nobody listening
	// - Block at read if channel is open and nothing to read
	// - gold rule : the goroutine that writes in a channel closes it after use
	ch := make(chan int) // default size is 1 !

	go func() {
		defer close(ch)
		ch <- 42
	}()

	received1, ok := <-ch
	if !ok {
		fmt.Println("channel closed")
	} else {
		fmt.Println(received1)
		received2, ok := <-ch
		if !ok {
			fmt.Println("channel closed")
		} else {
			fmt.Println(received2)
		}
	}
}