Catel - Part 5 of n: Building a WPF example application with Catel in 1 hour

using System;
using System.Collections.Generic;
using System.IO;
using System.Reflection;

namespace SocialMediaStream
{
    /// <summary>
    /// Factory responsible to create all <see cref="ISocialMediaProvider"/> instances.
    /// </summary>
    public class SocialMediaProviderFactory : ISocialMediaProviderFactory
    {
        #region Variables
        private static readonly List<ISocialMediaProvider> _providers = new List<ISocialMediaProvider>();
        #endregion

        /// <summary>
        /// Gets the <see cref="ISocialMediaProvider"/> instances in the current working directory.
        /// </summary>
        /// <returns><see cref="IEnumerable{ISocialMediaProvider}"/> containing all providers in the current working directory.</returns>
        public IEnumerable<ISocialMediaProvider> GetProviders()
        {
            lock (_providers)
            {
                if (_providers.Count > 0)
                {
                    return _providers;
                }

                string[] files = Directory.GetFiles(Environment.CurrentDirectory, "*.dll");
                foreach (string file in files)
                {
                    try
                    {
                        Assembly assembly = Assembly.LoadFile(file);
                        foreach (Type type in assembly.GetTypes())
                        {
                            if (type.IsSubclassOf(typeof(SocialMediaProviderBase)))
                            {
                                _providers.Add((ISocialMediaProvider)Activator.CreateInstance(type));
                            }
                        }
                    }
                    catch (Exception)
                    {
                        // Continue
                    }
                }

                return _providers;
            }
        }
    }
}