EventsBus.cs

using System;
using System.Collections;
using System.Collections.Concurrent;
using System.Collections.Generic;

namespace DIY
{
    /// <summary>
    ///    Represents dictionary with events, linked between publishers and subscribers.
    /// </summary>
    public class EventsBus
    {
        private ConcurrentDictionary<Type, IList> _events = new ConcurrentDictionary<Type, IList>();

	/// <summary>
	///    Adds a given subscriber to a chain of event-handlers.
	/// </summary>
        public void Subscribe<TEvent>(Action<TEvent> handler)
        {
            var handlers = GetOrAdd<TEvent>();
            handlers.Add(handler);
        }

	/// <summary>
	///    Triggers all subscribers of a given event.
	/// </summary>
        public void Publish<TEvent>(TEvent e)
        {
            var handlers = GetOrAdd<TEvent>();
            foreach (var handler in handlers)
            {
                handler(e);
            }
        }

	/// <summary>
	///    Returns a list of event-handlers, subscribed to a given event.
	/// </summary>
        private List<Action<TEvent>> GetOrAdd<TEvent>()
        {
            var handlers = _events.GetOrAdd(typeof(TEvent), _ => new List<Action<TEvent>>());
            return handlers as List<Action<TEvent>>;
        }
    }
}