public interface ITypeFinder {IList<Assembly> GetAssemblies();IEnumerable<Type> FindClassesOfType(Type assignTypeFrom, bool onlyConcreteClasses = true);IEnumerable<Type> FindClassesOfType(Type assignTypeFrom, IEnumerable<Assembly> assemblies, bool onlyConcreteClasses = true);IEnumerable<Type> FindClassesOfType<T>(bool onlyConcreteClasses = true);IEnumerable<Type> FindClassesOfType<T>(IEnumerable<Assembly> assemblies, bool onlyConcreteClasses = true);IEnumerable<Type> FindClassesOfType<T, TAssemblyAttribute>(bool onlyConcreteClasses = true) where TAssemblyAttribute : Attribute;IEnumerable<Assembly> FindAssembliesWithAttribute<T>();IEnumerable<Assembly> FindAssembliesWithAttribute<T>(IEnumerable<Assembly> assemblies);IEnumerable<Assembly> FindAssembliesWithAttribute<T>(DirectoryInfo assemblyPath);}

public class AppDomainTypeFinder : ITypeFinder {#region Private Fieldsprivate bool loadAppDomainAssemblies = true;private string assemblySkipLoadingPattern = "^System|^mscorlib|^Microsoft|^CppCodeProvider|^VJSharpCodeProvider|^WebDev|^Castle|^Iesi|^log4net|^NHibernate|^nunit|^TestDriven|^MbUnit|^Rhino|^QuickGraph|^TestFu|^Telerik|^ComponentArt|^MvcContrib|^AjaxControlToolkit|^Antlr3|^Remotion|^Recaptcha|^DotNetOpenAuth,";private string assemblyRestrictToLoadingPattern = ".*";private IList<string> assemblyNames = new List<string>();#endregion#region Constructors/// <summary>Creates a new instance of the AppDomainTypeFinder.</summary>public AppDomainTypeFinder() {}#endregion#region Properties/// <summary>The app domain to look for types in.</summary>public virtual AppDomain App {get { return AppDomain.CurrentDomain; }}/// <summary>Gets or sets wether app should iterate assemblies in the app domain when loading types. Loading patterns are applied when loading these assemblies.</summary>public bool LoadAppDomainAssemblies {get { return loadAppDomainAssemblies; }set { loadAppDomainAssemblies = value; }}/// <summary>Gets or sets assemblies loaded a startup in addition to those loaded in the AppDomain.</summary>public IList<string> AssemblyNames {get { return assemblyNames; }set { assemblyNames = value; }}/// <summary>Gets the pattern for dlls that we know don't need to be investigated.</summary>public string AssemblySkipLoadingPattern {get { return assemblySkipLoadingPattern; }set { assemblySkipLoadingPattern = value; }}/// <summary>Gets or sets the pattern for dll that will be investigated. For ease of use this defaults to match all but to increase performance you might want to configure a pattern that includes assemblies and your own.</summary>/// <remarks>If you change this so that assemblies arn't investigated (e.g. by not including something like "^MTA|..." you may break core functionality.</remarks>public string AssemblyRestrictToLoadingPattern {get { return assemblyRestrictToLoadingPattern; }set { assemblyRestrictToLoadingPattern = value; }}#endregion#region Internal Attributed Assembly classprivate class AttributedAssembly {internal Assembly Assembly { get; set; }internal Type PluginAttributeType { get; set; }}#endregion#region ITypeFinderpublic IEnumerable<Type> FindClassesOfType<T>(bool onlyConcreteClasses = true) {return FindClassesOfType(typeof(T), onlyConcreteClasses);}public IEnumerable<Type> FindClassesOfType(Type assignTypeFrom, bool onlyConcreteClasses = true) {return FindClassesOfType(assignTypeFrom, GetAssemblies(), onlyConcreteClasses);}public IEnumerable<Type> FindClassesOfType<T>(IEnumerable<Assembly> assemblies, bool onlyConcreteClasses = true) {return FindClassesOfType(typeof(T), assemblies, onlyConcreteClasses);}public IEnumerable<Type> FindClassesOfType(Type assignTypeFrom, IEnumerable<Assembly> assemblies, bool onlyConcreteClasses = true) {var result = new List<Type>();try {foreach (var a in assemblies) {foreach (var t in a.GetTypes()) {if (assignTypeFrom.IsAssignableFrom(t) || (assignTypeFrom.IsGenericTypeDefinition && DoesTypeImplementOpenGeneric(t, assignTypeFrom))) {if (!t.IsInterface) {if (onlyConcreteClasses) {if (t.IsClass && !t.IsAbstract) {result.Add(t);}} else {result.Add(t);}}}}}} catch (ReflectionTypeLoadException ex) {var msg = string.Empty;foreach (var e in ex.LoaderExceptions)msg += e.Message + Environment.NewLine;var fail = new Exception(msg, ex);Debug.WriteLine(fail.Message, fail);throw fail;}return result;}public IEnumerable<Type> FindClassesOfType<T, TAssemblyAttribute>(bool onlyConcreteClasses = true) where TAssemblyAttribute : Attribute {var found = FindAssembliesWithAttribute<TAssemblyAttribute>();return FindClassesOfType<T>(found, onlyConcreteClasses);}public IEnumerable<Assembly> FindAssembliesWithAttribute<T>() {return FindAssembliesWithAttribute<T>(GetAssemblies());}/// <summary>/// Caches attributed assembly information so they don't have to be re-read/// </summary>private readonly List<AttributedAssembly> _attributedAssemblies = new List<AttributedAssembly>();/// <summary>/// Caches the assembly attributes that have been searched for/// </summary>private readonly List<Type> _assemblyAttributesSearched = new List<Type>();public IEnumerable<Assembly> FindAssembliesWithAttribute<T>(IEnumerable<Assembly> assemblies) {//check if we've already searched this assembly);)if (!_assemblyAttributesSearched.Contains(typeof(T))) {var foundAssemblies = (from assembly in assemblieslet customAttributes = assembly.GetCustomAttributes(typeof(T), false)where customAttributes.Any()select assembly).ToList();//now update the cache_assemblyAttributesSearched.Add(typeof(T));foreach (var a in foundAssemblies) {_attributedAssemblies.Add(new AttributedAssembly { Assembly = a, PluginAttributeType = typeof(T) });}}//We must do a ToList() here because it is required to be serializable when using other app domains.return _attributedAssemblies.Where(x => x.PluginAttributeType.Equals(typeof(T))).Select(x => x.Assembly).ToList();}public IEnumerable<Assembly> FindAssembliesWithAttribute<T>(DirectoryInfo assemblyPath) {var assemblies = (from f in Directory.GetFiles(assemblyPath.FullName, "*.dll")select Assembly.LoadFrom(f)into assemblylet customAttributes = assembly.GetCustomAttributes(typeof(T), false)where customAttributes.Any()select assembly).ToList();return FindAssembliesWithAttribute<T>(assemblies);}/// <summary>Gets tne assemblies related to the current implementation.</summary>/// <returns>A list of assemblies that should be loaded by the factory.</returns>public virtual IList<Assembly> GetAssemblies() {var addedAssemblyNames = new List<string>();var assemblies = new List<Assembly>();if (LoadAppDomainAssemblies)AddAssembliesInAppDomain(addedAssemblyNames, assemblies);AddConfiguredAssemblies(addedAssemblyNames, assemblies);return assemblies;}#endregion/// <summary>Iterates all assemblies in the AppDomain and if it's name matches the configured patterns add it to our list.</summary>/// <param name="addedAssemblyNames"></param>/// <param name="assemblies"></param>private void AddAssembliesInAppDomain(List<string> addedAssemblyNames, List<Assembly> assemblies) {foreach (Assembly assembly in AppDomain.CurrentDomain.GetAssemblies()) {if (Matches(assembly.FullName)) {if (!addedAssemblyNames.Contains(assembly.FullName)) {assemblies.Add(assembly);addedAssemblyNames.Add(assembly.FullName);}}}}/// <summary>Adds specificly configured assemblies.</summary>protected virtual void AddConfiguredAssemblies(List<string> addedAssemblyNames, List<Assembly> assemblies) {foreach (string assemblyName in AssemblyNames) {Assembly assembly = Assembly.Load(assemblyName);if (!addedAssemblyNames.Contains(assembly.FullName)) {assemblies.Add(assembly);addedAssemblyNames.Add(assembly.FullName);}}}/// <summary>Check if a dll is one of the shipped dlls that we know don't need to be investigated.</summary>/// <param name="assemblyFullName">The name of the assembly to check.</param>/// <returns>True if the assembly should be loaded into app.</returns>public virtual bool Matches(string assemblyFullName) {return !Matches(assemblyFullName, AssemblySkipLoadingPattern)&& Matches(assemblyFullName, AssemblyRestrictToLoadingPattern);}/// <summary>Check if a dll is one of the shipped dlls that we know don't need to be investigated.</summary>/// <param name="assemblyFullName">The assembly name to match.</param>/// <param name="pattern">The regular expression pattern to match against the assembly name.</param>/// <returns>True if the pattern matches the assembly name.</returns>protected virtual bool Matches(string assemblyFullName, string pattern) {return Regex.IsMatch(assemblyFullName, pattern, RegexOptions.IgnoreCase | RegexOptions.Compiled);}/// <summary>Makes sure matching assemblies in the supplied folder are loaded in the app domain.</summary>/// <param name="directoryPath">The physical path to a directory containing dlls to load in the app domain.</param>protected virtual void LoadMatchingAssemblies(string directoryPath) {var loadedAssemblyNames = new List<string>();foreach (Assembly a in GetAssemblies()) {loadedAssemblyNames.Add(a.FullName);}if (!Directory.Exists(directoryPath)) {return;}foreach (string dllPath in Directory.GetFiles(directoryPath, "*.dll")) {try {var an = AssemblyName.GetAssemblyName(dllPath);if (Matches(an.FullName) && !loadedAssemblyNames.Contains(an.FullName)) {App.Load(an);}//old loading stuff//Assembly a = Assembly.ReflectionOnlyLoadFrom(dllPath);//if (Matches(a.FullName) && !loadedAssemblyNames.Contains(a.FullName))//{//    App.Load(a.FullName);//}} catch (BadImageFormatException ex) {Trace.TraceError(ex.ToString());}}}protected virtual bool DoesTypeImplementOpenGeneric(Type type, Type openGeneric) {try {var genericTypeDefinition = openGeneric.GetGenericTypeDefinition();foreach (var implementedInterface in type.FindInterfaces((objType, objCriteria) => true, null)) {if (!implementedInterface.IsGenericType)continue;var isMatch = genericTypeDefinition.IsAssignableFrom(implementedInterface.GetGenericTypeDefinition());return isMatch;}return false;} catch {return false;}}}

public class WebAppTypeFinder : AppDomainTypeFinder {#region Fieldsprivate bool _ensureBinFolderAssembliesLoaded = true;private bool _binFolderAssembliesLoaded = false;#endregion#region Ctorpublic WebAppTypeFinder() {this._ensureBinFolderAssembliesLoaded = true;}#endregion#region Properties/// <summary>/// Gets or sets wether assemblies in the bin folder of the web application should be specificly checked for beeing loaded on application load. This is need in situations where plugins need to be loaded in the AppDomain after the application been reloaded./// </summary>public bool EnsureBinFolderAssembliesLoaded {get { return _ensureBinFolderAssembliesLoaded; }set { _ensureBinFolderAssembliesLoaded = value; }}#endregion#region Methods/// <summary>/// Gets a physical disk path of \Bin directory/// </summary>/// <returns>The physical path. E.g. "c:\inetpub\wwwroot\bin"</returns>public virtual string GetBinDirectory() {if (HostingEnvironment.IsHosted) {//hostedreturn HttpRuntime.BinDirectory;} else {//not hosted. For example, run either in unit testsreturn AppDomain.CurrentDomain.BaseDirectory;}}public override IList<Assembly> GetAssemblies() {if (this.EnsureBinFolderAssembliesLoaded && !_binFolderAssembliesLoaded) {_binFolderAssembliesLoaded = true;string binPath = GetBinDirectory();//binPath = _webHelper.MapPath("~/bin");
                LoadMatchingAssemblies(binPath);}return base.GetAssemblies();}#endregion}