var catalog = new AssemblyCatalog(typeof(Program).Assembly);
var parent = new CompositionContainer(catalog);var filteredCat = new FilteredCatalog(catalog,def => def.Metadata.ContainsKey(CompositionConstants.PartCreationPolicyMetadataName) &&((CreationPolicy)def.Metadata[CompositionConstants.PartCreationPolicyMetadataName]) == CreationPolicy.NonShared);
var child = new CompositionContainer(filteredCat, parent);var root = child.GetExportedObject<Root>();
child.Dispose();

[PartMetadata("scope", "webrequest"), Export]
public class HomeController : Controller
{
} 

var catalog = new AssemblyCatalog(typeof(Program).Assembly);
var parent = new CompositionContainer(catalog);var filteredCat = new FilteredCatalog(catalog,def => def.Metadata.ContainsKey("scope") &&def.Metadata["scope"].ToString() == "webrequest");
var perRequest = new CompositionContainer(filteredCat, parent);var controller = perRequest.GetExportedObject<HomeController>();
perRequest.Dispose();

using System;
using System.ComponentModel.Composition.Primitives;
using System.ComponentModel.Composition.Hosting;
using System.Linq;
using System.Linq.Expressions;public class FilteredCatalog : ComposablePartCatalog, INotifyComposablePartCatalogChanged
{private readonly ComposablePartCatalog _inner;private readonly INotifyComposablePartCatalogChanged _innerNotifyChange;private readonly IQueryable<ComposablePartDefinition> _partsQuery;public FilteredCatalog(ComposablePartCatalog inner,Expression<Func<ComposablePartDefinition, bool>> expression){_inner = inner;_innerNotifyChange = inner as INotifyComposablePartCatalogChanged;_partsQuery = inner.Parts.Where(expression);}public override IQueryable<ComposablePartDefinition> Parts{get{return _partsQuery;}}public event EventHandler<ComposablePartCatalogChangeEventArgs> Changed{add{if (_innerNotifyChange != null)_innerNotifyChange.Changed += value;}remove{if (_innerNotifyChange != null)_innerNotifyChange.Changed -= value;}}public event EventHandler<ComposablePartCatalogChangeEventArgs> Changing{add{if (_innerNotifyChange != null)_innerNotifyChange.Changing += value;}remove{if (_innerNotifyChange != null)_innerNotifyChange.Changing -= value;}}
}

using System;
using System.Collections.Generic;
using System.ComponentModel.Composition;
using System.ComponentModel.Composition.Hosting;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;namespace FilteringCatalogsSample
{class Program{[ImportMany]public IEnumerable<IMessageSender> Senders { get; set; }static void Main(string[] args){Program p = new Program();p.Compose();foreach (var item in p.Senders){item.Send("Hi,MEF");}Console.ReadKey();}void Compose(){var catalog = new AssemblyCatalog(typeof(Program).Assembly);var parent = new CompositionContainer(catalog);var filterCatalog = new FilteredCatalog(catalog,def => def.Metadata.ContainsKey("methods")&& def.Metadata["methods"].ToString() == "sms");//var AggrContainer = new CompositionContainer(filterCatalog, parent);var child = new CompositionContainer(filterCatalog);child.ComposeParts(this);}}interface IMessageSender{void Send(string msg);}[Export(typeof(IMessageSender))]public class EmailSender : IMessageSender{public void Send(string msg){Console.WriteLine("Email sent:" + msg);}}[Export(typeof(IMessageSender))]public class SecureEmailSender : IMessageSender{public void Send(string msg){Console.WriteLine("Secure Email sent:" + msg);}}[Export(typeof(IMessageSender))][PartMetadata("methods","sms")]public class SMSSender : IMessageSender{public void Send(string msg){Console.WriteLine("SMS sent:" + msg);}}
}