I'm creating custom UnityEvents for a game. The base class looks like this:
public class EventSO : ScriptableObject
{
List<UnityAction> listeners = new List<UnityAction>();
public virtual void Raise() { ... }
public virtual void AddListener(UnityAction listener) { ... }
public virtual void RemoveListener(UnityAction listener) { ... }
}
Sometimes I want to pass variables to an event. So I inherit:
public class FloatEventSO : EventSO
{
List<UnityAction<float>> listeners = new List<UnityAction<float>>();
public override void Raise(float f) { ... }
public override void AddListener(UnityAction<float> listener) { ... }
public override void RemoveListener(UnityAction<float> listener) { ... }
}
My goal is to be able to create ScriptableObjects for individual events I can then assign and invoke: a good example for a Float event might be to communicate game times. So, a ScriptableObject named "OnEveryHalfSec", for example.
The first problem with this approach is that I'll need to make a new class for each combination of variables passed to an event: UnityAction<float, int>, UnityAction<float, string>... and so on.
The second problem is that I can't override the base class like I've shown above; Raise(float) can't override Raise(). So I have to re-define on every class.
Is there a better way to approach this problem?
CodePudding user response:
It looks like you should define
public override void Raise(float f) { ... }
as
public virtual void Raise(float f) { ... } in the base class
You didn't put "(float f)" in the base class
CodePudding user response:
You want to use generics!
Have a base class like e.g.
public abstract ParameterEventSO<T> : ScriptableObject
{
List<UnityAction<T>> listeners = new List<UnityAction<T>>();
public virtual void Raise(T value)
{
foreach(var listener in listeners)
{
listener?.Invoke (value);
}
}
public virtual void AddListener(UnityAction<T> listener)
{
listeners.Add(listener);
}
public virtual void RemoveListener(UnityAction<T> listener)
{
listeners.Remove(listener);
}
}
Now you can have as many derived classes as you need with specific types like e.g.
[CreateAssetMenu]
public class FloatEvent : ParameterEventSO<float> { }
or
[CreateAssetMenu]
public class IntListEvent : ParameterEventSO<List<int>> { }
or also
public class CustomArgs
{
public Vector3 Position;
public string Name;
public DateTime TimeStamp;
}
[CreateAssetMenu]
public class CustomArgsEvent : ParameterEventSO<CustomArgs> { }