5) Messenger

Messenger

The Messenger is a static application service for relaying events (messages) in a loosely coupled way. Any object may be "Published" through the messenger and handled by methods (or coroutines) through the app.

• Support for objects, structs, enums and interfaces

• Support for caching. This allows for publishing then subscribing and then receiving a message in that order. This is useful for one time messages like authentication.

• Use the IMessengerObject interface to add a Publish() extension method to your message.

• Supports [Subscribe] annotation. Using this annotation unlocks the Subscribe(object) helper method. This helper method allows for the subscribe of all decorated methods auto-magically.

• Support for coroutines event handling.

##Use

####Subscribing

Subscribing is the wiring of methods to the messenger. Methods must take a single argument of the message type they are handling. When a message of the appropriate type is publish the method will be called.

public class MyHandler: MonoBehaviour
{
    void Awake()
    {
        // Subscribe using the [Subscribe] annotation
        Messenger.Subscribe(this);
		
		// Subscribe manually
        Messenger<MessageType>.Subscribe(MyHandler);
					
        // Subscribe manually
        Messenger<MessageType>.SubscribeCortoutine(MyCoroutineHandler);
    }

    void OnDestroy()
    {
        // Unsubscribe using the [Subscribe] annotation
        Messenger.Unsubscribe(this);
		
		// Unsubscribe manually
        Messenger<MessageType>.Unsubscribe(MyHandler);
					
        // Unsubscribe manually
        Messenger<MessageType>.UnsubscribeCortoutine(MyCoroutineHandler);
    }

	[Subscribe]
	public void MyHandler(MessageType arg);

	[Subscribe]
	public IEnumerator MyCoroutineHandler(MessageType arg);
}

####Publishing

Publishing is the sending a message to subscribed members.

public class MyPublisher: MonoBehaviour
{
    void Awake()
    {
		var message = new MessageType();

		// publish using the IMessengerObject Extension Method
		message.Publish();

		// publish Manually
		Messenger.Publish(message);
    }
}

####Caching

Messages may be cached. When cached the message will be saved and issued to late subscribers.

// Cache the message
[CachedMessage]

// or

// Cache the message and clear the cache of old messages of the same type
[CachedMessage(OnePerType=true)]

public class MessageType : IMessengerObject
{

}