Adding extension for issue #205

src/Grace/DependencyInjection/IExportTypeSetConfigurationExtensions.cs

@@ -1,4 +1,6 @@
-using Grace.DependencyInjection.Impl;
+using System;
+using System.Reflection;
+using Grace.DependencyInjection.Impl;
 
 namespace Grace.DependencyInjection
 {
@@ -19,5 +21,34 @@ public static IExportTypeSetConfiguration PrioritizePartiallyClosedGenerics(
 
  return configuration;
  }
+
+ /// <summary>
+ /// Export a type set by a keyed interface
+ /// </summary>
+ /// <typeparam name="T"></typeparam>
+ /// <param name="configuration"></param>
+ /// <param name="keyFunc"></param>
+ /// <returns></returns>
+ public static IExportTypeSetConfiguration ByKeyed<T>(this IExportTypeSetConfiguration configuration, Func<Type, object> keyFunc)
+ {
+ configuration.ByKeyedTypes(type =>
+ {
+ if (typeof(T).GetTypeInfo().IsAssignableFrom(type.GetTypeInfo()))
+ {
+ var key = keyFunc(type);
+
+ if (key != null)
+ {
+ return new[] { new Tuple<Type, object>(type, key) };
+ }
+
+ return null;
+ }
+
+ return null;
+ });
+
+ return configuration;
+ }
  }
 }