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    <p>Doesn't look like it can be done. If you'll notice from my test code, <code>RegistrationBuilder</code> won't even export a class that is decorated with a <code>ExportMetadata</code> attribute (message: System.ComponentModel.Composition Warning: 102 : An Export specification convention that would apply to type 'test.MyClassA' has been overridden by attributes applied in the source file or by a prior convention). MEF attributes take precedence over Fluent configuration via <code>RegistrationBuilder</code></p> <pre><code>class Program { static void Main() { // importing class instance var mcc = new MyClassConsumer(); // type to export var typeToExport = typeof(MyClassA); Console.WriteLine("Type to export: {0}", typeToExport); var rb = new RegistrationBuilder(); rb.ForType(typeToExport) .ExportInterfaces(); var catalog = new AssemblyCatalog(typeof(Program).Assembly, rb); var container = new CompositionContainer(catalog); container.ComposeParts(mcc); // bombs if MyClassA's MetadataAttribute is not commented out Console.WriteLine("Imported property's type: {0}", mcc.MyClass.GetType()); Console.ReadLine(); } } public enum MyClassType { TypeA, TypeB } public interface IClass {} public interface IClassMetaData { MyClassType Type { get; } } [ExportMetadata("Type", MyClassType.TypeA)] // works if you comment this line public class MyClassA : IClass { } [ExportMetadata("Type", MyClassType.TypeB)] public class MyClassB : IClass { } public class MyClassConsumer { [Import] public IClass MyClass { get; set; } } </code></pre> <p>UPDATE: if you can add <code>[Export(IClass)]</code> to the classes you'd like to export, you can filter the catalog as shown below:</p> <pre><code>class Program { static void Main() { var catalog = new AssemblyCatalog(typeof(Program).Assembly); var filteredCatalog = catalog.Filter(p =&gt; { var type = ReflectionModelServices.GetPartType(p).Value; return typeof(IClass).IsAssignableFrom( type ) &amp;&amp; // implements interface you're looking for Attribute.IsDefined(type, typeof(ExportMetadataAttribute)) &amp;&amp; // has ExportMetadata attribute // check for Type == MyClassType.TypeA type.GetCustomAttributes(typeof(ExportMetadataAttribute), true).Any(ca =&gt; { var ema = (ExportMetadataAttribute)ca; return ema.Name == "Type" &amp;&amp; (MyClassType)ema.Value == MyClassType.TypeA; }); }); var container = new CompositionContainer(filteredCatalog); MyClassConsumer mcc = new MyClassConsumer(); container.ComposeParts(mcc); Console.WriteLine("Imported property's type: {0}", mcc.MyClass.GetType()); Console.ReadLine(); } } public enum MyClassType { TypeA, TypeB } public interface IClass {} public interface IClassMetaData { MyClassType Type { get; } } [Export(typeof(IClass))] [ExportMetadata("Type", MyClassType.TypeA)] public class MyClassA : IClass { } [Export(typeof(IClass))] [ExportMetadata("Type", MyClassType.TypeB)] public class MyClassB : IClass { } public class MyClassConsumer { [Import] public IClass MyClass { get; set; } } </code></pre>
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    1. POMEF RegistrationBuilder export specific Interface implementation
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    1. COCan it be done without the `[ExportMetadata]` attribute i.e. just have a class property that returns the enum value (like my example but without the meta data attribute)?
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    2. CONope - you have to use the standard `[ImportMany] IEnumerable<Lazy<T, TMetadata>>` and filter from there when composing your object.
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    3. COUpdated with another example that filters the catalog if you use the `Export` attribute
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