// Basic sends and receives on channels are blocking
// use select with a default clause to implement non-blocking
package main

import "fmt"

func main() {
	messages := make(chan string)
	signals := make(chan bool)

	// non-blocking receive
	// if a value is available on messages then select will take the <-messages case with that value
	// if not it will immediately take the default case
	select {
	case msg := <-messages:
		fmt.Println("received message", msg)
	default:
		fmt.Println("no message received")
	}

	// non-blocking send
	// msg cannot be sent to the messages channel, because the channel has no buffer and there is no receiver
	// Therefore the default case is selected.
	msg := "hi"
	select {
	case messages <- msg:
		fmt.Println("sent message", msg)
	default:
		fmt.Println("no message sent")
	}

	// use multiple cases above the default clause to implement a multi-way non-blocking select
	// here non-blocking receives on both messages and signals
	select {
	case msg := <-messages:
		fmt.Println("received message", msg)
	case sig := <-signals:
		fmt.Println("received signal", sig)
	default:
		fmt.Println("no activity")
	}
}