A custom yield instruction that waits for an arbitrary event

WaitForEvent.cs

using System;
using MacSalad.Core.Events;
using UnityEngine;

namespace AeLa.Utilities
{
    public class WaitForEvent<T> : CustomYieldInstruction
        where T : MSEvent
    {
        public override bool keepWaiting => keepWaitingInternal;

        protected bool keepWaitingInternal = true;

        private readonly Func<T, bool> predicate;

        public WaitForEvent(Func<T, bool> predicate = null)
        {
            this.predicate = predicate;
            EventDispatcher.AddListener<T>(EventListener);
        }

        protected virtual void EventListener(T e)
        {
            keepWaitingInternal = !predicate?.Invoke(e) ?? false;

            // remove listener if we're done waiting
            if (!keepWaitingInternal)
            {
                EventDispatcher.RemoveListener<T>(EventListener);
            }
        }
    }
}