message.gno

 1package message
 2
 3// TopicAll defines a topic for all types of message.
 4// This topic can be used to subscribe to message for all topics.
 5const TopicAll Topic = "*"
 6
 7type (
 8	// Topic defines a type for message topics.
 9	Topic string
10
11	// Callback defines a type for message callbacks.
12	Callback func(Message)
13
14	// Message defines a type for published messages.
15	Message struct {
16		// Topic is the message topic.
17		Topic Topic
18
19		// Data contains optional message data.
20		Data any
21	}
22
23	// Publisher defines an interface for message publishers.
24	Publisher interface {
25		// Publish publishes a message for a topic.
26		Publish(_ Topic, data any) error
27	}
28
29	// Subscriber defines an interface for message subscribers.
30	Subscriber interface {
31		// Subscribe subscribes to messages published for a topic.
32		// It returns the callback ID within the topic.
33		Subscribe(Topic, Callback) (id int, _ error)
34
35		// Unsubscribe unsubscribes a callback from a message topic.
36		// ID is the callback ID within the topic, returned on subscription.
37		Unsubscribe(_ Topic, id int) (unsubscribed bool, _ error)
38	}
39)