path: root/event/example_subscription_test.go

// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package event_test

import (
    "fmt"

    "github.com/ethereum/go-ethereum/event"
)

func ExampleNewSubscription() {
    // Create a subscription that sends 10 integers on ch.
    ch := make(chan int)
    sub := event.NewSubscription(func(quit <-chan struct{}) error {
        for i := 0; i < 10; i++ {
            select {
            case ch <- i:
            case <-quit:
                fmt.Println("unsubscribed")
                return nil
            }
        }
        return nil
    })

    // This is the consumer. It reads 5 integers, then aborts the subscription.
    // Note that Unsubscribe waits until the producer has shut down.
    for i := range ch {
        fmt.Println(i)
        if i == 4 {
            sub.Unsubscribe()
            break
        }
    }
    // Output:
    // 0
    // 1
    // 2
    // 3
    // 4
    // unsubscribed
}