DisposableAction.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace DisposeUtils
{
    /// <summary>
    /// Util class for implementing disposable using delegates.
    /// Latest version is here: https://gist.github.com/pmunin/e09ba0eacbbc31e28d6e
    /// </summary>
    public class DisposeAction : IDisposable
    {
        public DisposeAction(IEnumerable<Action> onDisposeEnumerable)
        {
            this.onDisposeActions = onDisposeEnumerable;
        }
        public DisposeAction(params Action[] onDisposeArray) : this(onDisposeEnumerable: onDisposeArray)
        {
        }
        public DisposeAction(Action<DisposeAction> config)
        {
            config(this);
        }

        IEnumerable<Action> onDisposeActions;
        public void OnDispose(Action onDispose, bool first = false)
        {
            var lstActions = OnDisposeActionList();

            if (first)
                lstActions.Insert(0, onDispose);
            else
                lstActions.Add(onDispose);
        }

        List<Action> OnDisposeActionList()
        {
            var res = onDisposeActions as List<Action>;
            if (res == null)
            {
                onDisposeActions = res = onDisposeActions == null ? new List<Action>() : new List<Action>(onDisposeActions);
            }

            return res;
        }

        public void Dispose()
        {
            if (onDisposeActions != null)
                foreach (var da in onDisposeActions)
                {
                    da?.Invoke();
                }
        }
    }


    public static class DisposeExtensions
    {
        /// <summary>
        /// Returns new Disposable, that dispose this disposable and all other specified together
        /// </summary>
        /// <param name="disposableToCombineWith"></param>
        /// <param name="disposables"></param>
        /// <returns></returns>
        public static IDisposable Combine(this IDisposable disposableToCombineWith, params IDisposable[] disposables)
        {
            var lstActions = new List<Action>(disposables.Select<IDisposable, Action>(d => () => d?.Dispose()));
            lstActions.Insert(0, () => disposableToCombineWith?.Dispose());

            return new DisposeAction(lstActions);
        }

    }
}