Addressed feedback from design meeting

Author: javiercn

src/Microsoft.AspNetCore.Mvc.Core/ApplicationParts/ApplicationPart.cs

@@ -7,49 +7,8 @@
 
 namespace Microsoft.AspNetCore.Mvc.ApplicationParts
 {
-    public class ApplicationPart : IEquatable<ApplicationPart>
+    public abstract class ApplicationPart
     {
-        private readonly IDictionary<Type, object> _features;
-
-        public ApplicationPart(Assembly assembly)
-        {
-            if (assembly == null)
-            {
-                throw new ArgumentNullException(nameof(assembly));
-            }
-
-            _features = new Dictionary<Type, object>();
-            Assembly = assembly;
-        }
-
-        public Assembly Assembly { get; }
-
-        public T GetFeature<T>()
-        {
-            return _features.ContainsKey(typeof(T)) ? (T)_features[typeof(T)] : default(T);
-        }
-
-        public void SetFeature<T>(T feature)
-        {
-            _features[typeof(T)] = feature;
-        }
-
-        /// <inheritdoc />
-        public bool Equals(ApplicationPart other)
-        {
-            return Assembly.Equals(other?.Assembly);
-        }
-
-        /// <inheritdoc />
-        public override bool Equals(object obj)
-        {
-            return obj is ApplicationPart && Equals((ApplicationPart)obj);
-        }
-
-        /// <inheritdoc />
-        public override int GetHashCode()
-        {
-            return Assembly.GetHashCode();
-        }
+        public abstract string Name { get; }
     }
 }

src/Microsoft.AspNetCore.Mvc.Core/ApplicationParts/ApplicationPartCollection.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc.ApplicationParts;
+
+namespace Microsoft.AspNetCore.Mvc.ApplicationParts
+{
+    public class ApplicationPartManager
+    {
+        public IList<IApplicationFeatureProvider> Providers { get; } =
+            new List<IApplicationFeatureProvider>();
+
+        public IList<ApplicationPart> ApplicationParts { get; } =
+            new List<ApplicationPart>();
+
+        public void PopulateFeature<T>(T feature)
+        {
+            if (feature == null)
+            {
+                throw new ArgumentNullException(nameof(feature));
+            }
+
+            foreach (var provider in Providers.OfType<IApplicationFeatureProvider<T>>())
+            {
+                provider.GetFeature(ApplicationParts, feature);
+            }
+        }
+    }
+}

src/Microsoft.AspNetCore.Mvc.Core/ApplicationParts/ApplicationPartManager.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.Mvc.ApplicationParts
+{
+    public class AssemblyPart : ApplicationPart, IExportTypes
+    {
+        private readonly Assembly _assembly;
+
+        public AssemblyPart(Assembly assembly)
+        {
+            if (assembly == null)
+            {
+                throw new ArgumentNullException(nameof(assembly));
+            }
+
+            _assembly = assembly;
+        }
+
+        public override string Name => _assembly.GetName().Name;
+
+        public IEnumerable<TypeInfo> Types => _assembly.DefinedTypes;
+    }
+}

src/Microsoft.AspNetCore.Mvc.Core/ApplicationParts/AssemblyPart.cs

@@ -1,12 +1,11 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-using System.Reflection;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
 
 namespace Microsoft.AspNetCore.Mvc.ApplicationParts
 {
-    public interface IApplicationFeatureProvider<T>
+    public interface IApplicationFeatureProvider
     {
-        T GetFeature(Assembly assembly);
     }
-}
+}

src/Microsoft.AspNetCore.Mvc.Core/ApplicationParts/IApplicationFeatureProvider.cs

@@ -0,0 +1,14 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections;
+using System.Collections.Generic;
+using System.Reflection;
+
+namespace Microsoft.AspNetCore.Mvc.ApplicationParts
+{
+    public interface IApplicationFeatureProvider<T> : IApplicationFeatureProvider
+    {
+        void GetFeature(IEnumerable<ApplicationPart> parts, T feature);
+    }
+}

src/Microsoft.AspNetCore.Mvc.Core/ApplicationParts/IApplicationFeatureProviderOfT.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.Mvc.ApplicationParts
+{
+    public interface IExportTypes
+    {
+        IEnumerable<TypeInfo> Types { get; }
+    }
+}

src/Microsoft.AspNetCore.Mvc.Core/ApplicationParts/IExportTypes.cs

@@ -18,6 +18,6 @@ public interface IMvcBuilder
         /// <summary>
         /// Gets a list of <see cref="ApplicationPart"/> instances that compose the application.
         /// </summary>
-        ApplicationPartCollection ApplicationParts { get; }
+        ApplicationPartManager Manager { get; }
     }
 }

src/Microsoft.AspNetCore.Mvc.Core/DependencyInjection/IMvcBuilder.cs

@@ -18,6 +18,6 @@ public interface IMvcCoreBuilder
         /// <summary>
         /// Gets a list of <see cref="ApplicationPart"/> instances that compose the application.
         /// </summary>
-        ApplicationPartCollection ApplicationParts { get; }
+        ApplicationPartManager Manager { get; }
     }
 }

src/Microsoft.AspNetCore.Mvc.Core/DependencyInjection/IMvcCoreBuilder.cs

@@ -42,21 +42,21 @@ public static IMvcCoreBuilder AddMvcCore(this IServiceCollection services)
                 throw new ArgumentNullException(nameof(services));
             }
 
-            var collection = GetApplicationPartCollection(services);
-            services.TryAddSingleton(collection);
+            var partManager = GetApplicationPartManager(services);
+            services.TryAddSingleton(partManager);
 
             ConfigureDefaultServices(services);
             AddMvcCoreServices(services);
 
-            var builder = new MvcCoreBuilder(services, collection);
+            var builder = new MvcCoreBuilder(services, partManager);
 
             return builder;
         }
 
-        private static ApplicationPartCollection GetApplicationPartCollection(IServiceCollection services)
+        private static ApplicationPartManager GetApplicationPartManager(IServiceCollection services)
         {
-            var collection = GetServiceFromCollection<ApplicationPartCollection>(services);
-            if (collection == null)
+            var manager = GetServiceFromCollection<ApplicationPartManager>(services);
+            if (manager == null)
             {
                 var environment = GetServiceFromCollection<IHostingEnvironment>(services);
                 if (environment == null)
@@ -69,15 +69,15 @@ private static ApplicationPartCollection GetApplicationPartCollection(IServiceCo
                 }
 
                 var assemblies = new DefaultAssemblyProvider(environment).CandidateAssemblies;
-                collection = new ApplicationPartCollection();
+                manager = new ApplicationPartManager();
 
                 foreach (var assembly in assemblies)
                 {
-                    collection.Register(assembly);
+                    manager.ApplicationParts.Add(new AssemblyPart(assembly));
                 }
             }
 
-            return collection;
+            return manager;
         }
 
         private static T GetServiceFromCollection<T>(IServiceCollection services)