Go语言中的观察者模式

package main

import (
    "fmt"
    "time"
)

// Msg represents the message being passed between publisher and subscribers
type Msg struct {
    Data string
}

// Publisher represents the subject in the Observer pattern
type Publisher struct {
    listeners []chan *Msg
}

// Subscriber represents the observer in the Observer pattern
type Subscriber struct {
    Channel chan *Msg
    ID      int
}

// NewPublisher creates a new Publisher instance
func NewPublisher() *Publisher {
    return &Publisher{
        listeners: make([]chan *Msg, 0),
    }
}

// NewSubscriber creates a new Subscriber instance
func NewSubscriber(id int) *Subscriber {
    return &Subscriber{
        Channel: make(chan *Msg),
        ID:      id,
    }
}

// Sub adds a subscriber's channel to the publisher's list of listeners
func (p *Publisher) Sub(c chan *Msg) {
    p.listeners = append(p.listeners, c)
}

// Pub publishes a message to all subscribers
func (p *Publisher) Pub(m *Msg) {
    for _, c := range p.listeners {
        // Sending to channel may block. Use non-blocking send.
        select {
        case c <- m:
            fmt.Printf("Published message to subscriber\n")
        default:
            fmt.Printf("Subscriber channel is full, skipping message\n")
        }

    }
}

// ListenOnChannel listens for messages on the subscriber's channel and processes them
func (s *Subscriber) ListenOnChannel() {
    for data := range s.Channel {
        fmt.Printf("Subscriber %d received: %s\n", s.ID, data.Data)
    }
}

func main() {
    publisher := NewPublisher()

    subscriber1 := NewSubscriber(1)
    subscriber2 := NewSubscriber(2)

    publisher.Sub(subscriber1.Channel)
    publisher.Sub(subscriber2.Channel)

    go subscriber1.ListenOnChannel()
    go subscriber2.ListenOnChannel()

    // Publish some messages
    publisher.Pub(&Msg{Data: "Hello Subscriber 1 and 2!"})
    publisher.Pub(&Msg{Data: "Another message!"})

    time.Sleep(1 * time.Second) // Allow time for messages to be processed

    close(subscriber1.Channel) // Signal subscriber1 to exit
    close(subscriber2.Channel) // Signal subscriber2 to exit
    fmt.Println("Finished")
}

Published message to subscriber
Published message to subscriber
Subscriber 1 received: Hello Subscriber 1 and 2!
Subscriber 2 received: Hello Subscriber 1 and 2!
Published message to subscriber
Published message to subscriber
Subscriber 1 received: Another message!
Subscriber 2 received: Another message!
Finished