im making a game and want to code a event function. Example:
public void OnEvent(string args[]) {}
This function should be accessable through every script, like the Start() or Update() 'event' that you just need to call as function to be registered.
Any ideas?
Unity Events
Unity has a set of delegates, UnityAction, that have generic versions that accept up to 16 params.
Unity also has a set of events, UnityEvent, that also have generic versions with up to 16 params.
Unity events are used in the UI system for linking events (such as On Click of Button) to an action (a function in a script). These can be saved with the scene and are editable from the inspector, unlike the vanilla C# events and delegates.
These are both found in the UnityEngine.Events namespace.
Event Class example
private UnityEvent<string[]> myEvent = new UnityEvent<string[]>();
public void RegisterForEvent(UnityAction<string[]> action)
{
myEvent.AddListener(action); // register action to receive the event callback
}
public void UnregisterEvent(UnityAction<string[]> action)
{
myEvent.RemoveListener(myAction); // unregister to stop receiving the event callback
}
private void RaiseEvent()
{
myEvent.Invoke(new string[] { "Hello", "World" }); // raise the event for all listeners
}
Some Other Class example
private UnityAction<string[]> myAction
private void OnEnable()
{
// Create the action if it doesn't already exist
//
if (myAction == null)
myAction = new UnityAction<string[]>(EventCallback);
// Register to the event
//
otherScript.RegisterForEvent(myAction);
}
private void OnDisable()
{
// Unregister from the event when this object is disabled or destroyed
//
otherScript.UnregisterEvent(myAction);
}
private void EventCallback(string[] values)
{
Debug.Log("My action was called!");
}
Alternatively..
This can be accomplished with the event and delegate keywords. You create a delegate which is the method signature for the callback, and define an event that uses this delegate. Methods register to the event using += and unregister from the event using -=. Events Programming Guide for C#
You want to make sure to utilize OnEnable and OnDisable for registering/unregistering events in Unity, regardless of which route you decide to take.
UnityAction (literally an alias for delegate) and UnityEvent use delegates. I was hoping that UnityEvent.AddListener would be using light-weight references that don't need unsubscribing as we did with certain WPF 3rd party toolkits.
WeakReference. We'll have to sit down and replicate that functionality in our Unity projects :)The principal reason for following the WeakEvent pattern is when the event source has an object lifetime that is potentially independent of the event listeners. Thanks for finding that portion of the source.