Events

Event - used to exchange information between systems or user services

• Presented as a custom structure with data

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Example:

public struct WeatherChanged : IEvent { 
    public WeatherType WeatherType;
}

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Requires registration in the world between creation and initialization

World.Create(WorldConfig.Default());
//...
World.Events.RegisterEventType<WeatherChanged>()
//...
World.Initialize();

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Creation and basic operations:

// The event system will be created when World.Create is called and destroyed when World.Destroy is called
World.Create(WorldConfig.Default());
World.Initialize();
//...

// Before sending an event, the receiver of the event must be registered, otherwise the event will not be sent.
// Receiver can be registered after calling World.Create (e.g. in the Init method of the system).
var weatherChangedEventReceiver = World.Events.RegisterEventReceiver<WeatherChanged>();

// Deleting an event receiver
World.Events.DeleteEventReceiver(ref weatherChangedEventReceiver);

// Important! The lifecycle of an event: the event will be deleted in two cases:
// 1) when it's been read by all registered receivers.
// 2) when it will be suppressed on reading (by calling Suppress or SuppressAll method (information below) ) )
// So it is important that all registered listeners read the events or the event is suppressed by any listener so that there is no accumulation of them

// Sending an event
World.Events.Send(new WeatherChanged { WeatherType = WeatherType.Sunny });

// Sending default event value
World.Events.Send<WeatherChanged>();

// Get a dynamic identifier of event type (see “Component Identifiers”)
var weatherChangedDynId = World.Events.DynamicId<WeatherChanged>();
// Send default event value (Suitable for marker events without data)
World.Events.SendDefault(weatherChangedDynId);

// Receiving events
foreach (var weatherEvent in weatherChangedEventReceiver) {
    Console.WriteLine("Weather is " + weatherEvent.Value.WeatherType);
}


foreach (var weatherEvent in weatherChangedEventReceiver) {
    // True if this listener is the last listener to read this event (means that the event will be deleted after reading).
    bool last = weatherEvent.IsLastReading();
    // Returns the number of unread listeners other than the given listener at the moment
    int unreadCount = weatherEvent.UnreadCount();
}

foreach (var weatherEvent in weatherChangedEventReceiver) {
    // Event suppression - the event will be deleted and other receivers will no longer be able to read it
    weatherEvent.Suppress();
}

// Suppress all events for a given receiver
weatherChangedEventReceiver.SuppressAll();

// Marks the reading of all events for this receiver
weatherChangedEventReceiver.MarkAsReadAll();