void RaiseChanged <T>(ComponentHandler <T> handler, Entity entity,
Option <T> previousOption, Option <T> currentOption) where T : IComponent
{
T current; var hasValue = currentOption.TryGet(out current);
T previous; var hasPrevious = previousOption.TryGet(out previous);
if (hasValue)
{
if (!hasPrevious)
{
handler.RaiseAdded(entity, current);
Added?.Invoke(entity, current);
}
}
else if (hasPrevious)
{
handler.RaiseRemoved(entity, previous);
Removed?.Invoke(entity, previous);
}
handler.RaiseChanged(entity, previousOption, currentOption);
Changed?.Invoke(entity, previousOption.Cast <IComponent>(), currentOption.Cast <IComponent>());
}